[can I share namecheap/hostgator/godaddybluehost etc affiliate link in Fiverr with my clients?]

Please do not this, this will count as a fiverr TOS violation

[No response from client when I delivered the project.]

I think you can talk to fiver support.

[I recently join on Fiverr and Create a Gig]

If you are new seller, You can minor edit, minor edit means one topic just like tag/description/price

[My Gigs Are not appear in search]

https://www.fiverr.com/support_tickets/selling-on-fiverr/gigs check your gig status, If some gigs are not active, send a request to fiver support about the gig

[Why lying about your skills will never work]

After opening new gig, you can edit the gig after 24 hours, and if you get an order, it's better not to edit the gig, then it may lose rank.