A conditional offer is an offer to purchase a property which has a clause that requires the buyer to sell another property before they can purchase this one.  These can be quite confusing with many details so ask your realtor to fully explain how conditional offers work.

If you just need to upgrade the electrical panel to 200 amps, about $1200 should cover it.  However, if you also have to upgrade the entrance to the house, you would be looking at quite a bit more cost. 

The most important thing about an exclusive listing is that it can't be found on MLS.  It is a listing through one company and has to be sold through that company.  It can be advertised in newspapers, personal websites, etc. but won't be found on the largest website of all-MLS.  Since over 80% of homes for sale are found on MLS, it's not a good idea for sellers to list exclusively because your listing won't be seen by nearly as many potential buyers.

If you built a home today, your septic tank will likely be concrete with a field.  If build properly, they can be zero maintenance and may not ever have to be pumped out.  In the past, you could put any type of septic tank in including:  steel tanks, fiberglass tanks, pressure treated wood, or even just a barrel in the ground with a pipe going into a ditch instead of a proper drainage field.  Contact the Dept. of Health regarding new construction septic systems. 

This depends on the realtor who lists your home.  The most important advertising is on MLS (multiple listing service) which is where most buyers look for homes.  Most buyers look for homes on the internet these days.  There are many other websites used to advertise homes for sale as well such as:  the company's website, personal websites, Kijiji, etc.  However, many properties are still advertised in local newspapers, real estate guides, etc.  When interviewing realtors, ask them how they will advertise your home for sale.