You'll get a lot of suggestions and all are based on personal opinion, so, here's one.
Angle Cosine or Degree either one. Great if you're hunting where shots will be uphill or downhill. Angle or Degree, the software can handle it.
Kestrel 4500??? I'd go with the 3500 at about $180 or so. It'll do all you'll need and you can probably get it even cheaper by shopping around. If you're not anal about all variables, you could even go with the 2500 as a lot of people do.
Ballistic Program: Exbal and the NF software are one and the same.
Hand held Pc etc. You can go with a Palm for about $100.oo or even cheaper if you shop around on Ebay. It'll run the same software, just the Palm version and do everything you need in the field. If you have to do windows application while hunting then you'd need the Pocket PC and windows. You'll also spend a lot more money.
Field proven drop charts are a must.
I think you'll find that most go with a 6-9" Harris with PodLoc. The PodLoc lets you pivot the gun until it's level and then you flip the lever and lock it in place. You can get both from Triad Tactical, Inc.
. I carry 2 bipods a lot of the time if I'm setting up in an easy to get to spot. Also can shoot off a pack etc. Might also look at a good 2 or even 3 legged separate bipod although it will not be good for the really long shots.
Under the rear some use home made bags some use rabbit ear bags, some use their off hand and one that I carry with me is the RedMan rear bag. You can also get it from Triad.
I'd also recommend a ScopeLevel and something similar so you know when the gun is perfectly vertical. If you don't watch this it can be a killer at long ranges.
If you're gonna be shooting prone in the sticky stuff, you may want to invest in a good shooting mat. It'll save your equipment and body.
Then you may want to also include some good glass in the form of binoculars and spotting scope for finding the critters.