AFAIK there is a fixed fee for all new connections to ESB and this includes all pole transformers and lines required to get the power to your site. It will be your responsibility to get the power from this location to your meter box via and underground duct.
Site clearance should not be a big problem. Just and excavator and couple of trucks to draw away the stumps etc. Make sure you retain as much topsoil as possible.
Advice?
Spend plenty of time thinking about the layout of your new house, it is normally too late to make changes by the time you realise a room is too small or you have not included enough storage like walk in wardrobes or utility rooms. It might be a good idea to invest in a book of plans, have a look through them and use any elements you like in your own design.
If you can afford it use an architect who will listen to you and design a house that will suit you both now and in the future.
Use any south facing aspect to good effect so that sunlight can warm up your house during the day. It actually makes a huge difference.
Try and do up a realistic budget and stick to it. Remember you will be paying it back for the next 20 or 30 years.
If you are going for a contractor, get as many quotes as you can. You would be very surprised at the range of prices that come back to you.
Again, if using a contractor, involve a solicitor and get yourself a cast iron contract done up. At least then both you and the contractor will know exactly where you stand and there is no ambiguity about your and their responsibilities which can often lead to conflict. Chances are that any good contractor will have his own standard contract. Thats fine but make sure to read the small print and get it checked by your solicitor anyway.
I've plenty more but that should keep you going for a while
Best of luck with it.