scanning pics (what dpi setting)

[glenpinn]

hi everyone.

i am in the process of archiving all my older family photos dating from as early as 1921 up till 1980 and need to scan these photos ready to print them at 6x4 size.
some of the very old photos are very small in size (3"x"2 or 2"x2" or 4"x3" etc) and some are big (5x7) so i have decided to stick the photos onto both sides of coloured A4 card and slip them into clear plastic folder sleeves and then store them in a nice presentation folder.

after i layout and stick the photos to each page, i want to scan the pages in my canon scanner, then crop each idividual photo from the scanned pages and re-size the photos in picture-it to 1015x1524 (4x6) and get them printed.

my scanner default setting is A4 size, 100% magnification @ 75dpi scan resolution, 75dpi output resolution and the scan size is 618x875 pixels and if i scan at that setting the photos are very poor quality when magnified to say 100%.
i scanned the old photos using 400% magnification @ 300dpi scan res, output res was still 75dpi and the scan size was 2475x3503 pixels and when magnified to 100%, each of these photos is so crystal clear compared to the scan using default setting.

what i need to know is will the photos print at better quality using 300dpi scan res than if scanned at 75dpi scan res.
i know that i need to scan the small pics at a higher dpi setting to enable me to resize them to print at 1016x1524 (4x6) so do i actually scan at a higher dpi setting for smaller pics as opposed to say scanning larger pics, or is it safe to just use say 300dpi scanning for all photos no matter what size or age or condition the original photo might be.

one thing for sure, the file size of each A4 page when scanned at 75dpi is about 200kb, and the same page scanned at 300dpi is about 1.5mb.

also, is it possible to simply scan each page at say 300dpi and just have the whole page printed with all the photos printed at thier original size, i can then keep the printed A4 page without having to cut out each photo seperately.

any thoughts or am i confusing you ????........GLEN

i have attached one of my A4 sheets with 11 photos so u get a picture of what im trying to do.