RFB fixes most of the things that are fixable so your pretty good on that score. For realism you have a good start.
The fleetboat TDC and PK take some getting use to, work differently than Uboats.
RSRD is a good mod and it will send you to the right places but if you miss whatever it is that is in the area there isn't much else to shoot at so you have to freelance a bit.
This link will give you some good ideas about where to be and when to be there.
http://www.combinedfleet.com/battles These battles are well scripted in RSRD and can get quit exciting.
There are a ton of mods out there and as you get use to SH4 you'll want to check some of them out.
Welcome to the PTO
Magic