You would need drainage, but that can be added by just drilling some holes and then use something like a large lid as the drainage tray. Also don't forget to line the bottom of your pots with bits of clay or rocks instead of just straight soil to help drainage and allow some air to go through the bottom. (I use rocks from my road, backed in the oven to kill bugs about 1-2 inches deep with about an 1/2 of perlite on top of those and then cover that in the soil. (Hydro stones work the best imo along with broken plates and old pots but those can cost money) Size wise I'm not exactly sure, looking at a container I have that I believe is 18gallons would be perfect for 2 plants(Sounds like a lot of gallons but doesn't actually look that big so not sure) but basically just try to envision about the same amount of soil fitting in each section as would in each of your pots indivudually. I'll be at lowes tomorrow if you want me to get a more exact answer on that. As for the tips, generally when I hear of yellow/dieing tips pointed down I think of nute burn first but you said you have not actually given them any so far so could be something else. It could be that the time release fertilizers released all at once if you flushed the soil, but not sure if you did? Give this thread a look over and see if anything matches, Have A Plant Problem? Check Here First. . Also worth mentioning that from what I've seen the number one issue people have with plants when new to growing is trying to overread them and eventually over correcting and issue that really wasn't a big deal in the first place. So if its only on a tip or two and doesn't seem to be effecting the new growth then I wouldn't worry about it to much. (Pictures always help though if you are worried about it)

As far as nutes go, something local/cheap like all purpase miracle grow will work, but an organic line called Blue Mountian Organics sold on ebay can be had for I believe about 30 bucks for the entire line and is one of the best ive used. Basically during veg you want high N with lower P,K, and then that switches during flowering. (Should be listed on the front of all fertilizers as NPK in that order.) Theres also some guides in the organic section for making your own fertallizers from stuff you may have around the house, or just give google a search as many common things like apple skins, wood ash, ect have nutes in them and should be pretty much free.

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Usually high and randomly browsing threads so don't expect a reply beyond my original post as I've most likely forgotten I ever posted.