Hey there,
I've been playing the oboe for close to 10 years and have just finished my music degree on oboe, and have recently been correcting my tonguing technique because it has never really been secure for me - I have a lisp and T and D on an oboe reed doesn't work with my mouth like it does for others. When learning the oboe I heard a lot about T and D on the reed which is good when first learning the instrument as it gives you a basic idea of the tongue action. Instead of T or D, I think of tonguing with just behind the tip of the tongue onto the tip of the bottom blade of the reed. The tongue should sit as close to the reed as possible and move as little as possible in order to be clean. It should also have some kind of anchor, for me the tongue sits on my bottom lip.
In terms of the tongue action, think of the tongue moving back off the reed, and when put on the reed as flowing along with the air - like an arm muscle contracting to pick up something heavy (taking the tongue off the reed), and then instantly releasing and relaxing when the thing is dropped (tongue coming back on to the reed).
If you are getting spit in the reed, persist with the action, it may be a problem with your embouchure being too relaxed rather than the tongue action, give it time!
In terms of reeds I don't think I can help you as I don't know what scrape you are playing, but I assume it's American long-scrape (don't stress if you have no idea what that is!) so I'd probably go for La Voz, medium soft. It may be a good idea to see if there are any music stores or double reed suppliers around your area, often you can try reeds before you buy, and you know exactly which ones you are getting because oboe reeds can vary extremely. Ask your teacher also! He/she might have some ideas or put you in touch with someone who does.
Best of luck with your music making,
Daf