T-RIP is the specific T-800 Model 101 we see in Terminator Salvation.
T-800 are the terminators played by Arnold in T1 and T2. T-RIP in Salvation are quite superior to the future timeline's T-800 due to study of the T-850's remains.
I'm not sure what kind of terminator Marcus is. He seemed to be able to hold his own against the T-RIP in h2h combat. But he had vitals such as his heart.
What's confusing is that we him take bullets and know he's built like a terminator on the inside but we also see him get tackled Reece and he doesn't do any serious damage to those thugs in the fight scene where he's bprotecting Moon when they try to rape her.
Things started getting a tad confusing upon the release of T3. But before then the terminator Schwarzenegger portrays is a Cyberdyne Systems Model 101, meaning that all 101 terminators look like Arnold.
The 800 series is the number given to the terminatorís endoskeleton. The 800 also being the one Arnoldís terminator has.
Things got a bit muddled up when Arnoldís terminator said he was a T-101 in Terminator 3 and when his model number became T-850.
As for your first question - Yes the better machines have higher numbers.