i would definitely take the coral beauty off the list. they need a much larger aquarium. for info like that, check live aquaria...
i had a pair of clowns in my 29 and they turned aggressive. i had issues. moved them into my 75g and still had issues. got rid of them both and now have a single small ocellaris. they all have individual personalities though.
personally, i wouldn't add anything except maybe the goby. they stay in a different part of the water column.
i wouldn't be surprised if you have issues with the 4 fish you listed getting along. they all swim in the same part of the water and a 29g isn't very big. i had more than that i mine, and regretted it... i was told max out at a small fish for every 10g. everyone has their own opinions though...
anymore, i try to look at people that have been successful with their setups long term. can you squeeze in a couple more, sure... and ime, it will cause problems down the road.
if you want more fish, i would get a bigger tank... heck, i only have 7 small fish in my 75g and it seems cramped for them.
