Japanese translation help and book question

[SumireSatoh]

Don't mention. I'm glad to hear I could be of any help.
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5.) 彼の間合いのギリギリを頭に叩き込みなさい!

They run into a group of people protecting the target.

So would this be something like?:
"Get it into your head he is not at the right distance!"
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So, the word 「彼」here indicates the 'target', am I right? The sentence itself「彼の間合いのギリギリを叩き込みなさい」sounds a little awkward to me, not grammatically perfect at least. Something might be left out after 'ぎりぎり'.... anyway I think it could be「彼のギリギリの間合いを頭に叩き込みなさい」(here you can see a little difference in its word order.) , which means「彼の[動きの]正確なタイミングを頭に叩き込みなさい」,「彼の[動きの]タイミング（＝間の取り方）を正確に頭に叩き込みなさ い」or something like that.

My sentence might be awkward but I think it can be like:
'Get into your head the exact timing of his motion/movements'

27.)
今後はこのメンバーで活動するんだからしっかりとコミ ュニケーションは取ること！
Take the communication well in future because I am active with this member!
The whining person is now angry because some one made fun of his English.
"Because I have to deal with this member we should learn how to communicate better in the future!"
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The subject for the verb 活動するis 'you,' the hearers, or 'we,' the hearers and the speaker.
'From now on you/we all are going/supposed to work as regular members of this team. So you should learn to communicate with each other more effectively/without failure.'

Sorry my sentences may be awkward and explanatory so you may have to put them to more natural, better expressions.

[Chibibug]

Not at all, the more explanatory the better really! It really helps to see the progression from one sentence to another, especially in these sentences where pieces have been left out. That makes them really difficult to read! But, I guess they do that as a way of showing this is a casual conversation.

Thanks again for your help! It was very nice of you!

[SumireSatoh]

Not at all. I hope you'll enjoy reading manga. Have fun.(^O^)