can you add a paper wallet KEY ?
how do we do it ?
The key should be in WIF(wallet import format) for the importprivkey command (I believe).
I would expect that your papet wallet likely has your key in that format.
Nothing stopping you from trying, regardless. If you do, please report back with exactly what paper wallet software you used, and what your results were. We will post it in the OP post

By the way, I'm new to proof of stake "mining".
Does it do any kind of brute-force search to mine blocks? I see stuff about a "target" and see it using a fair bit of CPU.
Yes. It's basically CPU mining, but the client will only try to generate a block when it is actually eligible. It is not mining 24/7.
(Still, would be interesting if the client was able to outsource mining to an ASIC as necessary. Wonder if this can be done, and whether it would give you any advantage?)
Proof-Of-Stake uses something called the stakeModifier to prevent folks from brute forcing stake blocks.
Proof-Of-Stake is still new and essentially being tested, but has fared quite well thus far - CLAMS itself was in some ways an attempt at testing PoS, as we did not have a public mining period, i.e. as far as I am aware are the first truly PURE Proof-Of-Stake coin, though I may be missing an IPO or Giveaway coin I am unaware of.