1. Anyone shoot .270 winchester in these types of rifles? If not, why not?
Long action cartridges don't apply. Extra rifle weight, extra recoil, extra powder use, lower barrel life... The 270 doesn't have a great selection of high BC bullets available, and those which DO have high BC's will carry considerably more recoil than the 6.5 and 6mm's. Take note, the 6.5's dominated a handful of years, but the 6mm's are quickly taking over - the game is about managing recoil even despite awkward positions. The 270 isn't really punishing in comparison to other hunting cartridges, but compared to the PRS game rifles, it's a super magnum.
2. Difference between 6mm CR and 6.5CR for real life uses? And don't say .5mm
Less recoil in the 6mm. Better bullets and more makers of fast twist barrels are converting the game over to the 6mm's, I think we'll see fewer and fewer 6.5's in coming years, probably hanging around 20-25% eventually when the dust settles.
3. would a Ruger American in 6CM be a bad choice for a first rifle? Or a Savage of some sort? Do I need to spend a grand or more for the rifle? Like a Ruger Precision? I'm cheap. But I think I'd like to be able to shoot out to 800-1000 yards and actually hit.
Here's a reality - you need flawless feeding, because you WILL be on a stage where you're running the bolt hard and fast. Starting with a base model rifle and upgrading to be game worthy will see you spending FAR more than a Savage 10 Ashbury or RPR would cost out of the gate. You need a stiff stock or chassis, something which fits you perfectly, and ideally something adaptable for barricade blocks (MPA rail), and really ideally, something running AICS mags. Do the math on what your upgrades will cost and you might come close to breaking even, but you won't save nearly as much as it seems on first blush. I built a Savage 12FV into a practice rifle, MDT factory second chassis plus a LuthAR, magpul mags, cabela's sale and savage rebate = under $300 purchase price with tax... I'm sitting about $200 cheaper than buying an RPR or Savage 12 BA Stealth (but I have the longer chassis), and I had to use a blemished chassis to get there... Really didn't save enough to have made it worth my trouble. You might contact your local match directors or clubs hosting Club matches and talk about their gear and their match formats. We didn't run any here, at least none of which I was aware, but there's a Factory class option in the PRS now, it has price limits and modification limits - models like the 12 BA Stealth and the RPR or the Bergara 14 were supposedly the target, hopefully driving new blood by favoring turnkey factory rifles, and giving them a smaller pond away from the big sharks running the GAP's and Defiants. Might be an option if your local group is running them. There's also a gas gun series with AR-15 and AR-10/LR-308 classes, we only had one with our local this year, but it was nice to be able to drag out one of my AR's and be drop in competition ready.
4. I shoot long guns lefty... do I need a LH bolt gun? Is my right hand busy with the bag? remember I know nearly nothing about this type of shooting.
I personally would not recommend trying to run your rifle wrong handed. Whether you're busy with the bag, trying to support a "creatively flimsy" barricade, or cranking your turret and racing your action against a timed skills stage, you will not want to be running the wrong hand. I'm thinking about the typical barricade skills stage where you're taking a shot from 4+ elevations and hole positions in a Vtac style barricade, running the bolt, dialing, and moving your bag every shot. Now do it with the wrong hand... Screw that noise...
5. 6.5 CM is the new hotness but is there any real reason for its popularity? Is there anything that would be better for a tyro?
The 6.5 is already old news for the PRS matches. Wanna say the 6.5's were under 50% of the field the last two seasons? PRB's "What the Pros Use" articles would be a good start for exploring. The 6 Dasher, Creed, x47L, XC, SLR, etc are gaining ground, on the back of the super slippery 115's, and more and more guys trying to run free recoil (right or wrong) from any and all positions. I already have the reamer to convert my RPR to 6mm SLR when my 6.5 barrel gives up next year. I'm strongly considering putting a Dasher barrel on my Savage practice rifle for 2018 and fielding it as well.
The good news: You won't be married to any cartridge too long. You'll use up brass pretty quickly, and equally burn up barrels. I don't shoot much, definitely not enough, and I'm getting a new tomato stake every season. If you're not adverse to a little load rework, you can swap cartridges every season, or more frequently even, I've read the average guy in the top 100 of the PRS is running 4,000-6,000rnds per year, two barrels net (spread among a few rifles, of course).