Thinking about tackling water heater myself - how far would you go?

Backstory: This is my current water heater (installed by previous owners). It's a gas unit, located in the garage and on bricks. I'm in GA btw. Not a plumber but have experience with other DIY stuff - excuse me if I get the terminology wrong. This would be my first water heater install but have helped others do theirs.

Cold water supply has an old gate valve(multi-turn) then a soldered on copper flex pipe, then some kind of coupler threaded nipple then another flex pipe.

Hot water supply has same setup without the shut off valve.

Gas line looks relatively normal to me setup wise.

Here's my questions:

  1. Would you replace the cold water shut off valve with a ball valve then have a threaded end so you just have one large flex line going to the water heater? not sure why the old setup had the 2 lines with nipple.
  2. Also, would you replace the gas flex line and sediment trap/piping? Is it okay to leave the gas shut off valve?
  3. Would you put the new heater back on bricks? Would you install a pan? It's in a garage with good slope out - nothing valuable except cars

Thanks in advance. I'm just making sure I'm not going too far (but also going far enough). I had the thought of literally just unhooking the old and connecting new but thought better of it.

https://preview.redd.it/pt1u8zchaadd1.jpg?width=1536&format=pjpg&auto=webp&s=da4a490eb7f0134ce8b392795f02f46c0be7e24e

https://preview.redd.it/ch48j6dhaadd1.jpg?width=1536&format=pjpg&auto=webp&s=2dadfc4b3353c336a859f68ffe17a4ded46bbf45

https://preview.redd.it/9u7n4zchaadd1.jpg?width=1536&format=pjpg&auto=webp&s=360e78b37acfd6abb5accfa09f120b5a38755028

https://preview.redd.it/vbls50dhaadd1.jpg?width=1536&format=pjpg&auto=webp&s=5795976cfd6f9706e029673f796d10f585e4b8e4

https://preview.redd.it/67a1f1dhaadd1.jpg?width=2048&format=pjpg&auto=webp&s=67b1c891804c48213763d4691a5952e83cd741e9