I think you are setup for some 8ft tall or more plants my friend. When you run into problems fall back on your extensive research. Or come here and ask. Keep us posted.
Whats your ph? How much and how often do you feed it? How often do you water it? Ph imbalance can cause nute lock. Over feeding can scortch that thing. Over watering can cause root rot. Under watering can dry it out.
Damn. Looks like some sort of blisters. I never seen that before. Could the humidity be building water under the stems? It could be some sort of fungus.
Your ph must stay in between 5.5 and 6.5
The vegetative nutes should be fine. Just make sure you dont over do it.
The flowering nutes are not ideal but as you said you are limeted. They should work though.
Good luck my friend.
Im pretty sure that is supposed to be under the soil. Put it about a quarter to half inch under the soil. Water Wait 3 to 5 days. Water as needed un those days.