bro, need some advice

recently i bought 3050ub + type s alpine component + 4 channel prospec amp ps4.60(1600watts) + mohawk 12'woofer ms124

the question is
1) Izzit normal to use 2 channel on front and rear speaker?
2)izzit better to focus the 2 channel onto my component and the rear take it out?
3) since i use 2 channel for front and rear and 2 more for my woofer, would it be advisable to get another 2 channel amp for my woofer and the 4 channel amp for the front only?

i still new in ICE and all equipment above are based on my budget