Talk to the bike shop that sells the Treks and ask them if they would do a trade in for the new Trek- making adjustments for value of the two bikes of course.

Your Elite comes with 700x23 tires ...I bet its fork and brakes won't accept 'fat' tires above 25's.
The Trek 7.5 comes with 700x32 tires....way fatter than 23's.

Though making minor changes to a current bike you really want to keep can often work out well, my opinion is that every woman should have at least one bike that they truly love and are comfortable on.
Life is too short to spend a bunch of time and money trying to convert bike into something that it basically is not. Fixing up an old bike is something else again- more like a labor of love, and most older bikes are gotten cheap or free, not like your new Elite.
If you make a bunch of 'comfort' changes to this practically brand new Elite, it's value will be substantially lower when you go to resell it. It will not be what some other woman is looking for when they go looking to buy an Elite. You'll get the most money if you sell it now while it is still just like it was when it came out of the factory.