People like you need to include what damn state you live in with a question like this.
You need to have a business office, with regular posted 40 hours per week open, and - a gross receipts of $276,000 to keep your Class 1 FFL. Class 1 FFL is for people who sell guns - and if you do not have enough gross reciepts to prove you are a business and not a hobby - BATFE will shut you down..... and all the trouble you went through to get the license is a waste of time.
Class 2 - is for people who make silencers and machine guns. Some states do not allow you build itmes to sell to the public - 37 do.
Class 3 - is for people who sell silencers, machine guns and destructive devices. Some states do not allow you to sell to the public - 37 do.
Unless you are a person who is going to go into business - all off these are useless to you. If you don't mind spending $500 every three years, having the Class 2 is handy to buy, sell, swap, and trade suppressors - but if you decide to give up that license in 10 years or so, the toys you have acquired are no longer transferable. You die - they can be passed down to your heirs - but - this can be a huge, big, fricken hassel to your family!
The C&R is for collectors. It lets you buy, sell, and trade old firearms - firearms that are on the official BATFE listed web site for C&R transactions.
None of these are useful for concealed carry or using from state to state.
Each state has their own pistol permit program. Some states have reciprocity with other states - each state recognizes the others permits. Some states have no pistol permits - like Alaska - where anyone can open carry. Some states do not allow ownership or CCW of pistols.
For a complete list - go to www.opencarry.com