There are various possibilities for water bottles, depending on how you're packing your gear. Some bikepackers use camelbacks. Some use seatpost-mounted bottle cages - aquarack does one, and you'll find other examples on wiggle, chain reaction, various online suppliers.
As far as the amount of gear that can be carried is concerned, of course tastes differ. We have tourists posting here who manage to get 20lbs of gear, including sleeping bag and tent, into a large saddlebag plus a handlebar bag - no need for a frame bag, and 20lbs of gear, carefully chosen, will keep you comfortable on a multi-week tour. If you search this forum you'll find plenty of packing lists ( @
nun is especially informative in this respect) for various weights.
Personally I tour on-road and am happy using panniers, even though these days I'm unlikely to have much more than 25 lbs. If I'm not camping and out for less than a week I'll take a road bike with a Carradice saddlebag - maybe 15lbs. Obviously frame bags can be massively helpful if you're doing a lot of off-road stuff, especially if it's remotely technical.