Am not sure whether there will be an another crossover between Arrow and Flash. But, there's a possibility that characters like Felicity/Caitlin/Cisco may appear in both series. Also, there's another advantage to both series, because of happening in the same universe. Now both Felicity/Caitlin can help each other just via phone call/email. If Arrow team wants any info or equipment, they can just make a phone call to S.T.A.R labs, and get it done.
1. If he had beat Reverse Flash, there's no need of further episodes.

Btw, Barry is still learning how to use his powers and he's not fully owned the aspects of Speed Force. On the other hand, Reverse flash is from future and he's way way have better knowledge of the Speed Force (though its negative side). Oliver can only give him the physical/moral training to Barry, but to beat Reverse Flash - Barry must be a master of Speed Force.
2. Dr.Wells enters his Secret room, and pushes his Ring (You can see the Thunder lightning on reverse side in the ring), which signifies he is/he has some alliance with "Reverse Flash".
*i.kinja-img.com/gawker-media/image/upload/s--Ja-4mTvg--/c_fit,fl_progressive,q_80,w_636/ggkruw1amld2hqwfmb5y.jpg
In Comics, multiple speedsters (ofcourse the enemies of Flash) have owned the mantle of "Reverse Flash" (RF). There's one named Hunter Zolomon. He's the friend of Wally West (Descendents of Barry Allen), and he's sole purpose is to create havoc in every possible way, to project "Flash" (or the one who owns the mantle) as a hero.
It may be possible that
1. Dr.Wells is Hunter Zolomon, and the RF maybe his future self
OR
2. RF maybe future version of Eobard Thawne, Iris's love interest in the show. In the final fight scene, you can see RF killing all police officers except Thawne and West. Thawne even asks to West, why RF didn't kill him. If RF kills Thawne, his future self (RF) will be erased from the timeline. Maybe Eobard will turn into RF, in the upcoming episodes with/without the help from Dr.Wells.
And read this thread too: [LIKELY SPOILER] The identity of Reverse-Flash from tonight's episode. : FlashTV