Farms

It is global resource and work like any other mineral resource now. You don't outright get it, it slowly accumulate each turn instead, and get spend on a city each turn too.

Food doesn't accumulate.

After you've built all of your improvements that need Food, is there any reason to keep all of the farms? Can you re-purpose those tiles?

So, you get a few farms and build a city. If you don't find any more arable land, you get no more cities?! That sucks.

Farms have upgrades, at one point I had an excess of 30 food.

IMO, farms suck in Intrigue. I have played three games of Intrigue. If you get lucky with RNG, you will find one or two planets with one or two tiles of arable land. Build a farm, get a little food and build a city. Food quickly runs out, especially if your RNG roll craps out and you find one planet with one or two arable land tiles. Such is the case with my current game of 10 planets so far, one planet with two arable land tiles. That just sucks big time and is not realistic in any way. Really, one planet feeds an entire empire? Really? That is realistic?

Here is what is realistic. Any nation that relies on one small area or even one state to feed its entire civilization is a nation that will quickly lose out on the world stage. Hungry population means an angry population and a less secure state. Same is true on a galactic scale. 

On a positive note, I am enjoying all of the other additions with Intrigue. I love the governments and the market also. Too bad you can't trade for food...

Think of farms as buildings that raise your current food cap and cities as buildings that subtract from that cap.

I was unable to generate map to my liking in v3.0 (w/o Intrigue). After one game when one AI dominated all others after 60 turns (medium map, 6 players) I started to study the issue. So I ran the game with -cheat parameter so I could cheat the fog of war away in each map generated. I've generated about 10 universes with the same settings (medium map, 6 players) and every single time 2-3 starting positions had 5-10 class 10+ planets in the same radius (let's say 10-15 parsecs) while 2 positions had 2-4 lower than 10 class planets and the remaining positions had mix of around 5 lower and higher class planets. Which is a bummer, since those two races starting with only few <10 class planets are doomed to extinction from the start, making it effectively a game of 4 players instead of 6. So RNG is a bitch up to the point it makes your game worthless from the beginning. 

The point why I am talking about it is, that your only choice then for a balanced game is the map editor. This pushed me to edit the map Six Pillars from Map Pack DLC to keep it up to date - because of the lack of will to do it from Stardock in the first place. Some of those maps featured in that DLC offered nice balanced gameplay with equal amount of resources and planets for each player, which is great when you want to test yours or AI skills with the same pre-existing conditions for everyone, Six Pillars being one of them. But since major changes in Crusade those maps lack certain necessary trade goods and since v3.0 patch they lack arable land (although in v3.01 patch they introduced arable land generation to pre-v3.0 maps). Currently you can only add one Arable Land per planet in the map editor, but here is my updated version of the Six Pillars if you want to try it: https://steamcommunity.com/sharedfiles/filedetails/?id=1369246893

The game is purely won/lost in the opening colonising rush. It is just that simple. So as liqo_CZ just mentioned, the starting position ultimately determines your game and that of your AI opponents.

Personally farms are inconsequential. Find one planet with a farm or two close together and build Kimberly's Refuge. Stack a few farmers as needed. Food is now sorted for your empire. The rest are mostly bulldozed for better planet bonus stacking unless convenient to assist city pop bonuses. Obviously there is a little more to it with techs but that is the basis. Very easy to max out 20 planets with minimal effort and tile wastage. My current game against 15 godlike AI I have 450 pop with about 5 farms spread over 25 planets so it is not only feasible but effective

If we had open pop limits then farms might be an issue, but due to the tiny pops nowdays limited to just the planet class, I fail to see how this is still an issue for people. I miss the old days of having a few thousand pop in my empires. The thing is with this new system is the AI seems better able to use it making it more competitive which makes it an overall win in my book. I am sure most people have come to grips with how it works and adapted. I wish people would stop complaining and just learn how to adapt.

Back to the opening post, think of farms as a use it or lose it scenario. They produce X amount of food for that turn, which spoils and is unavailable for the next. But if you have cities, that food is now used to support/grow pop for that turn before it spoils.