还 vs 也 for expressing multiple actions Based on the structure:

S V O， 还/也 V O

When should I use 还 and when should I use 也?

A Chinese friend told me that 还 often sounds better than 也 in sentences where the two verbs are different, such as 我吃了炒饭，还喝了啤酒, and the reverse is true when the verbs are the same, such as in 我喜欢唱歌，也喜欢跳舞. He also said that 还 has a stronger emphatic sense of "not only, but also".

Are these assertions accurate in general? Are there any other key distinctions between 还 and 也 in this sentence structure?
I think what your Chinese friend said is pretty much right. 

In my opinion, 还 denotes the sense of "further more" or "to a larger extension". Well, 也 connects the two things with the same level of importance, severity, priority and etc.  

E.g. 我喜欢唱歌，也喜欢跳舞. can be simply paraphrased as 我喜欢唱歌和跳舞. 我喜欢唱歌，还喜欢跳舞. sounds like I like singing and moreover/furthermore I like dancing as well. Or Not only do I like singing, but also I like dancing. as your friend suggested.