1970's home with NO rough plumbing and drainage in the basement.
Cleanout and soil stack leaves house through foundation to septic at shoulder height.
Kitchen and powder above on main floor and 2 baths on upper level (all in the same corner of house).

Question: Can I tie into the existing drains and vents with a lift system for the toilet? Do you suggest jackhammering the slab or raise the shower for drainage?

1970's home with NO rough plumbing and drainage in the basement.
Cleanout and soil stack leaves house thru foundation to septic at shoulder height.
Kitchen and powder above on main floor and 2 baths on upper level (all in the same corner of house).

Question: Can I tie into the existing drains and vents with a lift system for the toilet? Do you suggest jackhammering the slab or raise the shower for drainage?

Yes you may install a holding tank and grinder pump and discharge into the main drain. However I fail to understand your question.
"Question: Can I tie into the existing drains and vents with a lift system for the toilet? Do you suggest jackhammering the slab or raise the shower for drainage?"
Are suggesting installing a false floor for the drainage for your bathroom group in your basement? You will also have to vent both the holding tank and the lavatory. You may not tie into any vent that another fixture discharges into. The vents will have to go out the roof or revent back into a existing vent at least 6" over the flood rim of the highest fixture that the vent services. Have you a system in mind? Regards, Tom

Basic question is: Can I add a bathroom in the basement? Which we can do as you answered with the holding tank and grinder pump.
Yes, I was referring to a raised floating floor for the bathroom fixtures- Is that the best solution
We don't have a system in mind, but don't worry- this is not a DIY- we will have a pro do the job. I was just trying to lay out the space and if I needed to allow room for steps up to the raised floor.
Your advice is much appreciated so I can have an intelligent conversation with the plumbing contractor.
Any other thoughts?

If you're planing on a raised floor to save the hassle of jackhammering up your basement you may be interested in a selfcontained unit. You will still have to make a outside sump but nothing like a rough in installed under a jackhammered basement floor. Check it out at;
http://www.sewagepumpsales.com/contractor-sewage-pump-outdoor-package.htm
More questions? I'm as close as a click. Good luck, Tom