What size entrance cable do I need to run a 200 amp underground service to my house? Meter wii be at the road, conduit is in place. Power company wants 6000. To run power back to the house, 1800. From across the road to a pole I'll have to erect. Another question. Can the pole I install be steel pipe instead of a treated pole?

You would need to use #500 sized aluminum cable. Also, you need to verify that the conduit you have installed is the correct size for the cable.

I do not know if the SE comes in 500 cmil size or not, you may have to use three single cables.

The pole will h ave to meet the utility's spec, so you'll need to ask them.

As for the cable/wire, why 550' of secondary? Did no one suggest running primary and transformer closer to the house?

The utility company wants close to $6000 to run the primary to within 120 feet of the house. If I set my own pole at the road and install everything else they'll run 74 feet of overhead to my pole for $1800

The utility company wants close to $6000 to run the primary to within 120 feet of the house. If I set my own pole at the road and install everything else they'll run 74 feet of overhead to my pole for $1800
OK, so what do you think will that remaining 476' cost you?
Where do you live. Most times the customer is responsible for underground wire. The utility might want 6 grand, but an electrician will probably cost you $4-5 grand for the same thing.
Once you get into the distance you are talking about nothing is cheap.

Either way, no way I'd run secondary 550'.

Again, to run 550' you would need to spend close to $3500, before tax and shipping on the cheapest rate I could find on the web.

Also, your conduit would have to be trade size 4 for RMC conduit or trade size 5 for schedule 80 PVC conduit. Any size smaller would not meet the code standards.

Stan's suggestion are much better than the costs plus labor plus the costs for renting the proper equipment to do the trenching.

All of this assumes that the Utility will allow you inside their boxes to make connections at both ends, transformer and meter base.