I can't get Captain Veleth to give me the quest. I have completed March of the Dead. Any ideas?

Try speaking to 2nd Councillor Arano. Captain Veleth is normally just supposed to give you the message to go speak to him. Not sure why he isn't doing that, so try the Councillor.

I had the same problem, so I went and did a few other quests for folks around town and a day or two later, Veleth approached me and the quest began.

Do a few other quests, wait a day or two, and he should approach you.

Do the quest where you need to get the book for the 2nd councilors wife

I got the book for the counselor's wife. Did a few other side quests. No random Morag Tong requests and I cannot get the Served Cold quest. Waiting...

Do the raven rock mine quest

This. Pretty sure you need the mine open to get things moving.

Crap! I did the Raven Rock Mine quest with another character and was going to put off doing it for a while with this character as it was a looooooooong dungeon...

Do the Rock Raven Mine quest, then the March of the Dead, and there is another quest about finding the stash of wine. After that, then you get the quest for that leads to getting the house.

I completed the Raven Rock mine quest and Ol' Captain Veleth walked right up to mr and gave me the quest. That was fun! Had a small problem as I couldn't get the last gate open to get at the bad guy. Fortunately, I was able to kill him through the grate and he died close enough that I was able to loot his body through the grate.

The Morag Tong that came at me and Janessa wee using tactics on us. It was cool.

Yeah, it took me awhile to figure out how to open that last gate. In the room next to the spike traps, where you pull the chain to open the gates...there are two chains, next to each other on different pillars. Pull both and that last gate will open.