Is there a multi Sig Explorer or Stats provider? Is there a resource where I can get the past and current number of multi sig transactions, all types?
Are you looking for 'bare multisig' transactions by BIP-11?

Have a look here: https://webbtc.com/stats and here: https://webbtc.com/scripts/multisig

Or may be you are interested in BIP-16 mostly used for multisig?

Take this link: http://p2sh.info