Howdy castcreator, and welcome to CPF,
First, here are some links you will find helpful:
CPF Welcome Mat:
http://www.candlepowerforums.com/vb/showthread.php?277224-The-Welcome-Mat-a-FAQ
Don't worry about reading the whole thing, just bookmark it, then glance through it. It will help you become familiar with the lingo we use around here.
If you like flashlights, at some point you will want to start using rechargeable batteries. This next site will help you begin learning about the various types available and the proper use and handling of those batteries, as some types can actually be a bit dangerous if not used correctly.
Battery University:
http://batteryuniversity.com/
Some neat flashlights to look at:
Flashlight review sites:
http://www.light-reviews.com/reviews.html
http://www.sliderule.ca/flashlight.htm
http://www.lygte-info.dk/review/Reviews UK.html
Now, to your question about Maglite mods. Learn how to use the
Google Search box at the top left of most CPF pages. Leave it checkmarked for "CPF Only" and it will limit it's search to relevant CPF threads.
For instance, enter "Mag mods", or "Maglite upgrades" and you will get a page with many threads about those subjects. It's also handy for finding threads about a particular flashlight you might be interested in.
We also have an area here on CPF devoted entirely to
modding:
http://www.candlepowerforums.com/vb/forumdisplay.php?17-Homemade-and-Modified-Flashlights-Discussion
And, an area for disscussing flashlight electronics, including batteries and chargers:
http://www.candlepowerforums.com/vb/forumdisplay.php?9-Flashlight-Electronics-Batteries-Included
So, there you go. Get a cup of coffee and settle in for some reading. Don't be in a hurry, it takes time to absorb all this new stuff, but then of course, that's half the fun!