Flexibility of word classes in Chinese I have just started learning Chinese and I know that 姓 can be both a verb and a noun. I wondered whether there are a lot of other Chinese verbs that can also be used as nouns. 
For example, is a sentence like 我要吃 a grammatically correct sentence in Chinese? Or better (since in this example 吃 cannot be interpreted as a verb): 这个 吃很好.
There are lots of words that can be both verb and noun. As you said， 姓 is one of them. I don't have a full list for all of them.

As for 吃， most of time it's a verb. 

In 我要吃, 吃 is a verb. To be more clear, you can put a target for it, like 我要吃饭；我要吃水果； etc.

这个吃很好 is unnatural. It should be 这个很好吃. 很好 is an adverb modifying the verb 吃. 

One case in which 吃 is used as a noun is 口吃，meaning stutter.