1) Impact Data books and TAB covers. If you know what you want/need and have time to wade through the options, you can spec out exactly what you need from them and tailor it to your mission/purpose.
However, in the LE/SWAT sense, we separated the "data book" that would give appropriate DOPE for an activation from the "record log" and target binder of all targets shot that or more for administrative/record purposes.
What Chris says is true, but always have a backup. Batteries die, apps fail to load (or weird shit happens after updates), or lighting can be an issue. ALWAYS have a hard copy somewhere.
2) For precision, ATLAS CAL. The Cal doesn't pan like the more popular V8. Harris is fine, but advances have been made and Harris isn't exactly cheap (at least do the Badger Ord interface if you do Harris. By the time you spec out a Harris right, you've already put in as much coin as you would for a stouter bipod. As Chris mentioned, have other feet options
3) We used Manfrotto and Slik/HogSaddle when we got into the game. We now run Really Right Stuff SOAR rigs. The aforementioned Manfrotto and Hog are rated for something like 20-25lbs where as RRS starts at like 70lb weigth and on up into 90 and 110lbs. Everybody asks the question: "Is a $1k tripod worth it?" Well, how much is it worth to you to be able to shot at the same accuracy off a tripod as you would prone off a bipod? I'm talking like no sling-wrap on the the leg, counter weight, special support technique stuff, just you, rifle, bipod. Quite possibly the BEST money that can be spent in the game.
4) The Rifles Only is very nice for sling use, but the bungee doesn't help in terms of anchoring or wrapping for use with tripods. TAB is a tried-and-true sling design. Have used Vickers Padded as well; it's fine but hardware (the slide) can be in the wrong place with doing sling-aided with appropriate tension. Depending on what kind of tripod you use, that will probably dictate how you'll be using the sling.