1) Do not get a fixed powder scope unless you know you want one. They are fine for most situations, but you don't have the flexibility of a reasonable variable power scope.
For example, I like to have at least 15x to practice my marksmanship. Is 15x necessary to hunting? No.
- Most of my hunting scopes max out at 10-12x. I shot my last deer on 7x. Earlier that day, I passed on a deer at 25 yards. I was looking at him at 2.5x.
Until you get an idea of what you like, give yourself a scope that lets you experiment a bit. 2-8, 3-9, 2.5-12, or 3-15 scopes will all work.
2) With a Tikka, you can buy a really good rifle and upgrade later if you want. Other people have mentioned different stocks and other parts upgrades which have merit.
But, I want to focus on the flexibility the action gives you to swap cartridges. With prefit barrels and the ability to swap from a SA to a LA and back, you aren't committed to a cartridge if you don't like it.
Based up the description you provided, you can get a really nice Tikka (spring for stainless or a cerakoted version) in .243 that will do everything you want. It certainly won't beat you up in the configuration you described.
- With its standard bolt face, you can switch the rifle to 6CM, 6.5CM, 7-08 or 308 for the cost of a barrel. Alternatively, you can swap to any longer barrel if you feel the need. Want a carbon fiber barrel? No problem.
- With its standard bolt face, you can convert your SA Tikka to any of the 30-06 based cartridges for the cost of a barrel plus a few relatively inexpensive parts.