Yellow labs would be one of the few that do well in a 29G and I wouldn't put more than 4 or 5 in there.
Your filtration is fine, especially because yellow labs tend to take longer to get bigger (in my experience) so if you buy as juvies, it would be good.
I prefer NLS but its up to you.
The substrate depends on how many heavy rocks you will have and if you have any eggcrate in it. If you have eggcrate or not a lot of heavy rocks then an inch would be fine.
If no eggcrate and heavy rocks, make it a little more. Because a 29G is so tall it doesn't look bad either if you have it a little thick.
Your filtration is fine, especially because yellow labs tend to take longer to get bigger (in my experience) so if you buy as juvies, it would be good.
I prefer NLS but its up to you.
The substrate depends on how many heavy rocks you will have and if you have any eggcrate in it. If you have eggcrate or not a lot of heavy rocks then an inch would be fine.
If no eggcrate and heavy rocks, make it a little more. Because a 29G is so tall it doesn't look bad either if you have it a little thick.