I have played nearly 100 times, and only 3 times have I made it to the Goo.
This is a ROGUELIKE game, which are inherently supposed to be difficult, though it sounds like you're having worse luck than anyone else here, or indeed doing something wrong.
My main cause of death is starving (or being so low on health because of starving that mobs one-shot me).
I've played tons of times myself, and food is NOT that rare. You must be wasting tons of time and playing inefficiently, to be going through that much food. Don't stand around waiting for your HP to regenerate unless you absolutely have to.
*Equipment is far too rare, maybe 1 out of 5 runs will have a weapon/armor, and of those about 1/5 is usable due to strength, and those are ALWAYS without fail cursed.
Useable equipment IS rare. On levels 1-3, I just try to put things on without identifying. If they're cursed, I die/restart. If they're not, I try to use them until they're identified, and hopefully I have enough strength. The game IS hard, and if you get to level 3 and don't have any gear upgrades, you're pretty screwed.
*Potions are basically useless since you have to drink them to find out what they do and I almost never see a second one of the same color.
There are 2 types of potions essential to your survival - Healing and Strength. There are also Experience potions but those are very rare. Since they're so essential, you have no choice but to try to drink potions. I usually do it on level 2 or 3 when I'm down to ~half health. Stand in water (in case it's a fire potion), be ready to go through a door (to avoid poison/paralysis gas), and risk it. You have no choice but to do this. Welcome to a roguelike game!
*Scrolls are a little better since they are generally useful
IIRC, there's only ONE bad type of Scroll, and that's Challenge (calls all the enemies to you). I wouldn't read them unless you have a piece of equipment you want to upgrade/identify, because you don't want to waste those scrolls.
*Classes: Wizard is useless as there are no wands anywhere.
Chalk that one up to luck. If you DO get a wand (especially fireball) the Wizard can kick some serious butt, so good luck!
Warrior is mildly useless because the rogue does just as much damage (due to attack speed) while also using a lot less food. Warrior generally starves to death by the end of floor 3.
What makes you think the Rogue has a faster attack speed? I don't think that's the case, unless you're talking about Shuriken/knuckleduster, which are faster WEAPONS (they work the same for a Wizard), but do much less damage than the Warrior's sword. Warrior is far easier since you start with 11 Str and a better weapon that you can use 1 upgrade scroll on risk-free, AND when you eat any food, it heals you. If you're at full HP, wait until you've starved a bit until you eat, don't waste those potential HP. Plus, you get pre-identified Strength potions. Personally, I haven't found the rogue's 'eat-less' ability to be very useful. Again, you must be wasting TONS of time if you're having that much trouble with starving. Wait until you're actually Starving (not just hungry) before eating, and remember that healing wells 'feed' you, and rooms of regrowth heal you faster than starving will kill you.
You need to position yourself so that the monster is in the doorway before you whack them. Then they cannot dodge as well, and you kill them faster.
That's not true. The only difference a doorway makes is that you can funnel monsters and ensure you're only fighting 1 at a time, and if you manage to surprise a monster, the FIRST attack will have a bonus to it. Once the monster knows you're there, there's no combat advantage to a doorway.
you are probably missing some secret doors that lead to rooms with food in them. Because while food is rare enough that there is a challenge, it's not as rare as you state in my games.
On the first couple of levels, I don't see many hidden doors/rooms, but gravling's right that food is not that rare. If you've "completed" a level, but there is a large uncovered part of the map (which is always the same dimensions), it might be worthwhile to look for a hidden entrance.
Enemies almost never dodge my attacks as it is. And looking at the average damage, the warriors sword does 6, and the rogues knuckles does 3, but with the rogue attacking twice a round that is the same dps as the warrior. I will try the door thing though.
If you rarely miss enemies, consider yourself lucky. Warrior's weapon does more damage AND he starts with more Strength. It makes a big difference. As stated above - Rogue doesn't attack any faster, the knuckleduster is just a faster weapon. It says so right in the description.
I search anywhere that makes sense, but I dont have the time (because of the food bar) to search every single wall I come across. Something as basic and required as food should not be hidden behind doors, especially since the warrior takes so long to find them. Fighting rats? Okay there should be at least little piles of mystery meat. Gnolls? Should have some just sitting where I interrupted their meal. Food should not be this hard to find.
The game is very hard, and very rewarding when you manage to survive. Don't be so butthurt about it.
what about the fact that ALL gear (if there is any at all) you find is cursed? And that there are no wands or thrown weapons anywhere?
See above. It's rare enough, but not as bad as you're crying about.
I suggest you keep trying as Warrior until you manage to beat the Goo, since it's by far the easiest class. I've beat the game with all 3 classes. Good luck with your drops and your combat!