You seem to have been given a lot already, but I'm going to add my two pen'orth anyway.
I used to work in a military museum, and we had a lot of stuff pertaining to the Easter uprisings, because my regiment was involved. Now, thanks to the Ministry of Defence (War Department it was then) having a 50 or 75 year rule for publication, you'd think that the Easter uprising information would be available, in the same way that a lot of WWI stuff is now. BUT, the MoD being what they are, everything concerning Ireland back to Cromwell, and William III has been 'red flagged', meaning that it is still covered by the official secrets act, and unlikely to be published ever.... Yes, I know, typical really but there we go. If you get serious about researching this subject, you may come across this blockage, and I'm afraid there is nothing you can do, unless you are also subject to the British Official Secrets act, or have diplomatic status.... There has been a very successful wall built around this subject since it started - it was considered a serious threat to the war effort, taking valuable men away from the front, at a time when we could least deal with them, and what you do find is likely to have a mostly Irish viewpoint. However, there are some relatively good books giving a fairly even handed account of both sides, if you are willing to look for them. Look for sites that specialise in military history, and try to steer clear of anything stamped War Department or Ministry of Defence!!!