If you go full time, the training provider will teach you everything. If you go part time it's up to you.
You could go with CATS because they are half the price of Bgs - then use BGSonline anyway. You do the brush up exams, do the 2 or 3 weeks classroom stuff, and they endorse you to take the exams.
The whole process part time will take 6-12 months, so if you're working, get an ATP: you can self endorse. No requirement to buy a course or attention ground school.
If you're in the US, you can take the ground school and exams in Florida I think.
I think you have to take all the exams in the same country, but you can do the practical in a different one.
Once you take your last exam, you have 36 months to get your CPL and IR issued. You then have a rolling 7 years to get your ATPL issued.
It's a whole lot easier if you have a multi crew type rating and 500 hours multi crew - then you can just take the ATPL ride in a SIM. Otherwise you'll have to do the conversion courses for about £10k