I think starting now would be a great idea as it can take a couple of waxes to get a good finish if you have been shaving up to now.
Waxing is not comfortable but it isn't going to kill you either. Typically your first wax will be your worst because the hairs are quite coarse at the moment, but after waxing they come through much finer and softer. Take a couple of painkillers half an hour before your wax to take the edge off. I wax every month, no painkillers and don't find it painful.
A bikini is typically somewhere around the knicker line, though some go higher than others.
A brazilian is all hair off except for a vertical strip on the pubic mound.
I would recommend getting a hot or non-strip wax, though i know some waxers do well with the usual wax. I would also leave the hair for 4 weeks before your first wax and then book every 4 weeks.
Waxing usually improves ingrown hairs, though some people suffer more than others. Every 3 days, starting 3 days after your wax, use a buffing mitt over the bikini area. This will encourage hairs to grow out rather than in. Apply moisturiser daily and if you do get an ingrown hair, pop some savlon on it.
Good luck with your wax. I'm sure you will love it, i've never had a client go back after experiencing a wax xx