If separates, many hi-end enthusiasts swear by Marantz. Supposedly when it comes to electronics Japanese Marantz is a trusted/proven lieutenant. For Amp, you can look for suitable partner.
I think you’re worrying on Screen a lil too much. Unless there’s significant improvement (20% +), you can go via DIY route as well. Unless you can’t get same gain, ambient light rejection feature in local procurement, then go with best brand (not 5Lac one surely).
I got mine (material) from pro-cinema installer in Mumbai. Gives more flexibility to aesthetics (design panels, back wall etc the way you want).
Good luck!
Alright thanks! I will keep this thread updated with my decisions.