How much do megapixels matter?

Hello, i am stuck between the canon rebel t4i and the nikon d3200. The nikon has 24 megapixels, whilst the t4i has 18. I have a retina display macbook pro and i will be wanting to take pictures up to 2880x1800 in size. Can the t4i handle this? I like everything else about the t4i. I will be shooting pictures of nature and also taking video. Can you explain how many megapixels i need and what they do? Will i be able to take 2880x1800 pics with the t4i? With the d3200? all feedback is appreciated; thanks so much in advance :)
>>> How much do megapixels matter?

Best flash for portraits and other objects?

I have a Nikon D5000. I have just been using the automatic flash on my camera, but I want to improve the look of my portraits. I am totally clueless about what flash to get and would like some advice.what flash do you guys use? any tips?
Note: I may be covering a late afternoon wedding later this year, what would you suggest for this?
>>> Best flash for portraits and other objects?

Nikon lense and screen?

Hi, I recently purchased a Nikon D5100, I had the D3100 before and for some reason now Im annoyed by how u have to look through the watchamacallit to take a picture.Id much rather have it show on the screen like a point and shoot almost. Can anyone tell me how to switch the view? Thanks
>>> Nikon lense and screen?

Whats the nikon d5100 good for?

Im really intrested in buying the nikon d5100, im looking to buy a zoom lens for it! what do you recoomend? and whats the cheapest zoom lens i can buy for it? also what are some other cool lens to buy for this make? i also wondered, what exactly is this make of camera good for? like is it good for concerts, birthday parrties, family events, self pictures ?
>>> Whats the nikon d5100 good for?

My Nikon D5000 delays in taking pictures?

I am an Ametuer photographer, and I have a Nikon D5000, I've had it for about 2 years now, and it seems that when I'm taking pictures it takes a long time for the camera to actually take. I'm getting frustrated with my camera because I've missed SO many great facial expressions and perfect moments because my camera wouldn't take the picture. I don't understand why.Is it a setting on my camera? Maybe, something to do with the lens? I've used friend's Cannon cameras before and they don't do this, I'm considering switching brands, but I've got so much money invested in Nikon, I don't want it to be a waste. Help! any suggestions?
>>> My Nikon D5000 delays in taking pictures?

How to keep polycarbonate lenses clean?

No matter how hard i try they get so dirty so quick.they weren't cheap lenses either they were 200$. i clean them with the cleaning cloth they give me i still cant get them clean 100%. i run them under water and clean them but then they get dirty immediately. and they take forever to clean.i used to have nikon glass lenses and they cleaned up like a charm, run them under hot water and wipe them off and they were good.any ideas
>>> How to keep polycarbonate lenses clean?

WHY DO THE PICTURES COME OUT DARK ON MY NIKON D70S?

The flash fires up but the pictures come out dark in interiors on my Nikon D70S. Why is that happening?
Thanks for your help.
>>> WHY DO THE PICTURES COME OUT DARK ON MY NIKON D70S?

How to: 2nd Curtain Sync Flash photography?

What equipment do I need for 2nd Curtain Sync Flash photography? I have a Nikon D3200, is there anything special I must add to achieve this photography technique?
>>> How to: 2nd Curtain Sync Flash photography?

Is this depth of field?

I used my aunts really nice lens yesterday, and loved the results I got. Example:

http://www.flickr.com/photos/adripendletonphotography/8213247370/in/photostream/
and…
http://www.flickr.com/photos/adripendletonphotography/8212156149/in/photostream

They were taken with a Canon(not sure what model) and a 70-200 lens. What I really love about these is the way the background is so blurred out.Is this what depth of field is?

My new lens(the Nikkor 18-200mm VR) should be here within a week, and I'm wondering if the lens I'm getting is capable of making the backgrounds of my pictures like the ones I linked to above.My old lens(the standard kit lens) never did this for me.

So, is this depth of field? And how do I get results like that with my new lens - if possible?

Please excuse my ignorance - I'm pretty new to photography, but I'm learning quickly :)
Added (1). Jack - A? As in Auto? I think you may have meant manual, which is what I shoot in.
>>> Is this depth of field?

How macro is the nikon 40mm f/2.8 lens really?

Here is the lens I'm talking about:
http://www.amazon.com/Nikon-40mm-2-8G-Micro-NIKKOR/dp/B005C50H2Y
It supposively focuses at 6 inches, but I tested my 18-55 mm kit lens at 40 mm and it seems to focus around 6 in from the subject as well, but in no ways do I see it as a micro lens. How could this lens be macro if it focuses at the same focal length that my kit lens does?

I know it is probably irrelevant, but I have a nikon d3100.
>>> How macro is the nikon 40mm f/2.8 lens really?