Can Cryptocoins be spent through payment services? can Cryptocoins be spent through payment systems like Paypal? i.e. instead of linking to  a credit card, linking to the wallet address. or do they have to explicitly accept bitcoins/crytpocoins?
No, a cryptocurrency wallet does not itself have any link or correspondence to fiat (traditional) currency. If the payment processor doesn't explicitly support Bitcoin or other cryptocurrency, then they are not interoperable.