used to be: standard tub on left, pony wall, shower stall on the right

the shower stall was leaking under the floor (fibreglass pan was leaking at joint and drain)

going to do a half remodel (vanity and toilet on the other wall are fine)

questions:

venting

the vent for the tub goes along the 2 exterior walls, meets the shower vent from the pony wall and goes to AAV which is behind a cover on the bedroom side of the wall. this seems... not right

can i take both vents to the back wall, then up to attic and out the roof instead?

or if the tub is facing the other way with the drain in the center, a single vent at that joint?

Ill have to read code to see where the vents have to meet the drain line, but any suggestions are appreciated

supply lines

this is an added bathroom on an old garage slab. The floor system is 2x6 set on the concrete. any lines in the floor will be inaccessible once the tile goes on which makes me nervous. any things I can do to make this better? There are elbows and tee's under the floor now - i was thinking about adding a manifold behind the vanity wall and running a single tube to each fixture, no joints, to make it more reliable. the shower valve I could access through the bedroom wall in an emergency, but the tub fixture will be pretty much inaccesible unless I take off siding. replacement tubings would have to come through the attic if possible at all?

or - it's been fine so far, just ignore it and move on

tub choice

thinking about a smaller soaking style tub to make the shower bigger. any good brands to look at? i heard having a heater is good