We do this almost every year and in different ways depending on if we have AP's at Disney.
This year we have booked an entire package 4 nights at royal Pacific followed by 14 nights animal kingdom lodge with free dining and park tickets.
Flights with Lufthansa via Frankfurt.
I added the 14 day universal ticket bought in the U.K. It works out cheaper than buying from a US site, although prices have risen in the past 2 years.
I am registered with the US universal site and receive details of special offers including park admission. These tend to come out about a month in advance - not great if you're a planner. I have booked direct with universal in the past and found them helpful in trying to find a good deal.
Staying on site at certain hotels will give you the express pass which, to me, is essential at certain times of the year. That is regardless of where you buy tickets.
Disney travel will book your flights for any duration you request, so you can book a Disney package with free dining etc but arrive before or leave after those dates.
When we use our
DVC I will book flights myself either with the airline or with someone like Expedia where you often get a great deal inclusive of the universal hotel. They do tend to change from day to day so if you see a good price jump on it quick and don't look again.
Hope this helps.