Well I think you will need more dakka if you wll generally be facing hordes of orks.
I would suggest uping the number of tactical marines. If you can use some of the heavy weapons marines in the taticla squads if you have squads of 10.
Landraiders look cool, but the basic one is a poor point investemnt. I would probably suggest taking wither a landraider crusader or a redeemer. This is a personal choice depening on wether you want too shoot a lot or flame.
I would suggest a standard Captain as your lord, wih a power weapon. This should let him get used to challeneg rules witha chance of surviving.
10 terminators is a lot to take, but would be a hard formation to destroy for orks at least. Not sure if I could fit that many in a 1500 point list though.
This is a good start to fill out the points.
Your toast has been burnt and no amount of scraping will get rid of the black bits.