Lots of Question, Tweeters, speaker, amp

OK, I have some question,, I have a Dodge stratus which have 6.5 " speaker (front doors) but on tha panel there are like midranges like 3.5" and 6x9 rear speakers...... Everything have factory speakers and radio, Im putting the radio from my old car and I will be using the 6.5 a pair of Infinity component system, and at the rear 6x9 which i dont really care that much about the bass because i already have 2 10"subs so i have a Sony 6x9 they are going to be connect it to an amplifier which is rated 80x4 at 4 ohms. What I want to do is on the 3.5 holes where the midrange goes, i want to buy those Bullet Horn Tweeter and connected to the crossover of the infinity the one that says tweeters, I want to know if i can do that and what do you guys think about those tweeters....... ALSO the 2 question is what have to be the rating RMS of the speakers to match the amplifier, Because i have the change to sell my speakers to a friend and get some new ones, But i want to know what are the rms of the speakers that my amp can hold... THANK YOU for your HELP...

Or I dont know if this is possible, to have the component system (6.5 Doors) and add a 3.5 (i was looking at the soundstream 3.5) speakers coax in the holes (dash) and how would be the wiring to connect it to the amp... PLEASE HELP ME guys

I would ignore those infernal horns, I would mount the component woofer in the door and the tweeter in the 3.5" mounting location. More to follow when I have the time.Top Secret, I can tell you but then my wife will kill me.