2nd 5year plan isn't difficult once you get organised.

The hardest one is the coal requirement. You can do this by:
- excavation 1
- the coal in the urals focus
- the minister that gives +10% resource extraction
- changing to the foreign investment regulated (not sure if this is needed)

For the factory building write down what you need and work out where to build things. Initially, leave 2 open slots at Crimea, Minsk, etc. in case you get the Heavy Industry or Construction decisions for there.

Saratov is a problem and you may need to build some military factories and even an engine factory there. Otherwise, you should be able to get by with building only civs and a couple of power plants.

If you start focuses with the Politburo one (get Captain of Industry) then do the collective route to get + construction speed it is easier.

You need 3 fuel silos (I think) - you can get two from focuses but need to build one, just don't forget to allow a week for the fuel storage to fill.

Run your steel and aluminium production at whatever you can get energy for at start to get maximum benefit of trade. Cut it back as energy demand increases. Don't waste factories on spies or the agency. You should be able to afford one factory for rubber.

If you don't do the navy focuses it should be easy. If you do them you can cut the specialised defence industry and Kharkov improvements but it is tight.

You need 4 tractor factories (so 2 conversions) but I find 6 (4 conversions) works better.

PP goes on keeping up stability, some ministers and law changes, and GOSPLAN and foreign investments. Use tractors to increase land at each time.

Most important is, early 1937 queue up everything you need to construct to complete the plan. Put the longest ones at the top. Mid-year start juggling so all will finish before the deadline.

As regard the purge. The penalties more or less prevent you from any military ventures before the historical ones.

Pre-purge use the xp from border conflicts (you should win if Japan starts them). Army war games, and Spanish Civil War to get the WW1 doctrines you need to access WW2 doctrines. I then like to do the first in the Command tree to get increased army xp even though it will be delayed by the purge. Also like to get Professional Officers (+5% to doctrines) and Officer Development (+5% org) if have NSB.

Bleed the Spanish Civil War for army and air xp. Although, I find air xp will fill up as can't spend it on much before late 1938 when can do the focus that allows learn from mistakes.

Once war with Germany breaks out I find the air penalties are so great it is best not to use the bombers on the front just have fighters on intercept to get experience. Army experience should come in quickly to get rid of penalties. Usually, the penalties are down low enough to start counter-attacking in the winter.

I will also add that instead of wasting civilian factories converting to tractor factories, theirs a selection in the government tab that produces 200 factories per week. I think its under industrial focus or something, next to the electronics focus in the cabinet. it only costs 100 political power so if you chose that at the start after politburo, you dont need to build any more tractor factories to meet the quota. This saves you additional civilian factories. Its all really tight getting the criteria for the 2nd 5 year plan but doable. Last time i messed up a little and had to power build a few artillery factories since those are the cheapest.

It has all changed in the Test branch - haven't tried it yet.