1. one; 1
壱, 弌 and 壹 are used in legal documents
一メートルほどしか離れていないから、大丈夫だろう。Since it is only about a meter away, it should be fine.
2. best
3. first; foremost
4. beginning; start
5. a (single); one (of many)
before a noun
あくまで素人の一意見だからな。It's just one amateur's opinion, after all.
6. ace
7. bottom string (on a shamisen, etc.)