I have been pointed to the s70 t5 manual as THe Volvo to get for my needs and budget. I have $6,000 to spend on the car it self and I want to go no deeper than $10,000 total invested for car and mods.

Reliability and cost of ownership is most important. I need to count on this car as my only means of transportation. My intentions would be bolt ons and tune for power adders, springs and shocks for suspension, mild braking mods and some tasteful cosmetics. I'd drive it hard I'm sure but I really don't know what I'm getting into on the repairs, reliability and how tough these cars are... I have no idea about the weak spots if any.

Are these cars modify, change the oil drive hard with basic maintenance and get you to 200k miles without anything big going wrong? Or should I run like I would away from a VW, Audi or MB? I don't want a Japanese car... I just love boost and being different, I saw a nice clean Modded 850 I think the other day and it got my wheels spinning.

 

All S70's are older cars - age equates well with problems. T5 manuals are likely to have been driven hard already - hard driving also results in likely problems. You want to mod it and drive it hard - again, increased problems.
That said, any 13 year old performance car driven hard is going to be a wrench queen.
Generally, S70's do last a long time, handle well, and are reasonably easy to work on. Generally being the operative word here.