Elite: Dangerous PvE - Mobius

I would like to optimize jump range / cruise speed of both my Rattaconda and my Rasp for Fuel Rat rescue purposes.
Could anyone point me to the best engineers for that goal, or even to which materials would be required?
Also, I assume you have to be in the ship to be upgraded when visiting the engineer and can't upgrade other ships later, can you?

Thanks!
Your faithful Fuel Rat Uvelius

Farseer in Deciat.

http://inara.cz/galaxy-engineer/1

Elvira Martuuk is also another possibility. She's got Class 5 upgrades in FSD and Class 2 in Thrusters. She takes 3 Soontill Relics (Rare commodity in Cheranovsky City, Ngurii) for her opening contract. Only downside is that she's in the Khun system, which is on the opposite end of the galaxy from Farseer.

http://inara.cz/galaxy-engineer/2