1. Both options are fine, but it depends on the content
- "we completely understand the situation..."
- "we understand the situation completely..." - there should be an object ("situation") between the verb and the adverb.
- "we understand completely the situation"
About the placement: "completely" is an adverb (answering the question "how", describing an action, a verb).
I can think of several examples in which adverb stands before or after the verb in the sentence:
* She spoke quietly. (verb --> adverb) : the sentence is complete.
* She quietly said all what she had to say (adverb --> verb + object, the sentence must be continued)
I can't really explain the rules specifically, so maybe you should check it out in grammar books under "word order in a sentence" and "adverbs".
2. The sentence is not clear. Did you mean:
* Did you find it helpful?
* Was it helpful regarding what you needed?
* Did it answer all your needs?