Most firearms suggested in this thread are way too big IMO for the purposes you listed. Its often said a well tuned 30-06 is a 99% solution. I agree. A good load in that caliber will kill anything on the planet...laws on requirements for dangerous game notwithstanding. You can (literally) find a box of ammo anywhere if you need it, I even saw some in a gas station in Zimbabwe. Back in the day, Hemingway et.al. used the '06 on rhinos and elephants with 220 gr solids. You can get an off the shelf mountain sporter in Rem 700 stainless laminate or composite stock, or my favorite the SAKO 85 or if you have a fatter wallet the Fierce Firearm's CT Carbon edge. Browning, Winchester and Ruger also make some nice rigs in that caliber. One of the first three will weigh about 6.5 bs, be very portable and accurate with moderate recoil and muzzle blast. If you want some long legs put on a Viper Vortex 4-16X44 HS-T scope with custom turrets from Kenton industries. (bang for your buck option--you can go stupid on optics if you want). I recommend a good load in 165 gr bullet--my favorite is Sierra Game Changer as its a well known game killer and blended ogive give a high BC and SD. But there are many deadly and accurate bullets to choose from--Nosler partition, or Accubond, Barnes TTSX to name a few of my "go to" bullets. I load for 5 different 30-06 in the friends and family. We mostly load one of the bullets listed above, usually 165 gr (all around bullet) ahead of 57 grs. IMR 4350 (give or take), CCI BR-2 primer and Lapua brass or Nosler custom if we can get it. We get from 2820 fps in my Sauer 90 (sierra) to 2900 in my son's mountain sporter (Barnes TTSX) with a shorter barrel (?go figure?)
With our drop in turrets we easily ring the gong at 1000 yards and have plenty of juice left for shots on big game out to about 700 yds.