new digi cam questions

[redrs]

ok i just got a new camera. i got is a Samsung Digimax A7 7mp .i got the A7 for lil over $200($300+ in most places i looked). now for the questions.
1. i know kodak is a good brand of cameras and was suggested the samsung A7 over a kodak c643(6.1mp) and is around the same price($199) i paid for the samsung. will there be a noticable difference in quality/speed of the pics? i know the better mp should give better pics & better cropped shots; but im not to sure on how well samsung rates on camera quality. i prefer samsung for tv's over most of the other top brands.
2. i took the camera out and took pics of the fireworks on the 4th and had some success. it was slow on taking low light pics in the auto mode, so i switched the the fireworks mode and it was even slower on taking pics(several seconds) and with the slower speed it was taking i blurred the pics by not holding still(i know use a tripod but i dont have one yet) is there a way to speed up low light pics, since the fireworks mode is supposed to be low/no light dark pics. it takes pics quick in normal conditions and when using flash.
3. how big of a sd card can i use in the samsung. im sure i can use a 1gig, but i would like to know if i could use one of the 2-4 gig cards. i know its alot of space to fill, but in highest quality & res. i can only take around 100 pics with a 512mb card(x-media 80xcard). it may be alot of pics, but i want to make sure i would always have room for more pics. or would 2 or more 1gb be better/safer incase of card failure.
4. im not to sure on the quality of all the different brands & speeds of the aftermarket sd cards out there. most brands i have seen i have never heard of, or heard of them making flash memory. i was thinking of getting patriot or corsair or pny, since i have heard good things about their system memory, and i think they had lifetime warrentys on them. the other brands like pqi, a-data, ocz, and others, have similar priced cards in same sizes. are they just as good as the other named brands?
5. is the speed of the card really going to effect how fast i can take pictures(saving to card time) or is that more for when taking pics from card to pc? my current card is a x-digital 512 80x card i got from walmart due to price since it came with a card reader. it is a fast card from what i can tell, but i have never used any flash media before to base it from.
thanx for any help anyone can give me, new to the camera market and trying to learn.