instead of multiple threads you can also start multiple processes of the miner (incase you have problems with threads)
check how much MB Ram your vserver has and ensure that Threadcount*ram used per thread does not exceed your total ram (leave some ram unused for the OS) - if you violate that -> "killed"
to not leave putty on use the Scren application:
screen -S "name" opens a new screen (like a new browser tab)
then start your process and you can exit putty now
when come back use screen -r and your back where you have been
some miners have stats that are hard to understand as a beginner... you have to mine for a couple of hours or a full day (until some blocks are found) inorder to see how good your doing roughly - use the pool stats for this
there are tons of mining calculators out there, not sure if they work for PTS - but to use them you need a better understanding of what your doing and some stats (at least c/m or cpm)
i also rented 2 vservers - after testings my rough estimates are that i get 10% back of what i invested - especially when GPU mining of PTS is going now this value should even decrease
so if the servers arent free for you, you should just give it up

cheers