therere lots of crypto marketplaces nowadays. I guess its not a big deal to find the suitable one. Unfortunately I cannot advice you because i prefer using classic marketplaces.
no . crypto based marketplace are actually verry rare today due to the crypto adoption which isnt big enough .
i know some site online that accept crypto payments but those site are seems unsecure and they are not also reputable . so i dont recomend to try them though i heard that amazon , ebay and other popular stores are now starting to have a plan about crypto partnership . you'ld better for them because they are 100% legit .
Meanwhile the best thing you can do is to trade you coins unto local currency and buy directy on physical stores or convert them unto paypal or other ecurrency/payment method that most online stores accepts .