Don't think you'll need the extension tubes with a true macro lens unless you're after very high magnification ratios. Extension tubes are a bit hard to work with as you will have to focus manually and your DOF will become very thin. getting automatic extension tubes might still allow auto metering however focusing will be manual even if hte extension tube has the contacts to permit autofocus it will be very hard for the lens to focus.
Not familiar with resizing as I use photoshop for that, What I do is to resize the image to 1000 or 800 pixels at the longest size then decrease quality setting to get a file size around 100-300Kb. This way loss of resolution is kept to a minimum. Not sure how you can do that with Project without causing severe losss of resolution.
Macro mode on the camera does not allow it to focus any closer AFAIK what it does is to control focusing area and maybe metering to the common settings that work best with the selected preset. A macro lens will be a lot better for that purpose.
noise is visible in some of your pictures and mostly on this one.
http://i128.photobucket.com/albums/p...n/c0250001.jpg
noise results from higher ISO or longer exposure time. it appears more on darker areas of the pictures and amplifies when you increase the brightness of an underexposed shot.
you can try taking two pictures one at the lowest Iso setting on teh D40 (200 i guess) and one ona higher Iso 800 100 or 1600(don't know what the highest ISO on a D40) The difference betweent he two will be the added noise on the higher ISO image. it used to be called grain on film and it was very nice on film however in digital it just ruins hte picture.
It is still better to have some noise because of High ISO than to use lower Iso which will cause longer exposure and more risk of blurr. a noisy piture is still acceptable (to some extent) but a blurry picture is not. also you can decrease noise with dedicated noise reduction software but a blurry shot cannot be fixed.
make sure to post some pictures with the 105 VR when you get it.