Building pc help !

hello ,

I currently have :

Ryzen 5 5600

6750 xt

b550m aorus elite rev1.3

Corsair cx series cx 750 80 plus bronze

and I’m willing to upgrade to ryzen 7 5700x and Rtx 5070

1. can my mobo have this gpu because it is only pcie 4.0 and the gpu 5.0

2. can my psu handle all of these ? and does every brands gpu come with an adapter ?

3. which brand 5070 should i choose ? is everything the same and should go to the cheapest ?

thanks for all