Heya! Surv honestly has one of the most wholesome communities , and it would be great to see you around! 
All farms are allowed, except for zero tick farms, as said above. It’s worth noting that lag machines are not allowed either/ anything that could cause a large amount of lag, so if you’re unsure, check it with a mod. Lava can only be placed by an smod or higher, and costs 75g per placement, if you want to use lava for a farm. Also, pigmen do not drop gold (and there is no gold in the nether) as gold is the currency, so it would be a little overpowered.
These links might be useful:
Rules:
Summary
Guide:
Summary
Crates:
If you have any more questions, feel free to ask! 