Who wants to visit whom? In this sentence:

好久没有看望萧乾老人了，怕干扰他翻译和写作，怕影响他休养生息，但心里却常惦念着他。

I think 好久没有看望萧乾老人了, = 萧乾好久没有看望老人了， but I'm not certain and I don't know why I think this. Is there a rule of syntax being followed here?

Could it be read '老人很久没有看望萧乾了，'?

I think '怕干扰他翻译和写作' means '萧乾怕干扰自己的翻译和写作工作，‘ but I suppose it could be '老人怕干扰他。。。‘

Who does ‘看望，怕，休养生息， 惦念‘？Is that clear from this sentence?
Who does ‘看望，怕，休养生息， 惦念‘？Is that clear from this sentence?


Yes, but the subject is ommitted here, let's restore it:


  (我)好久没有看望萧乾老人了，(我)怕干扰他翻译和写作，(我)怕影响他休养生息，但(我)心里却常惦念着他。


This is verbose indeed, so it's natural to ommit it, especially in the writing at the view of first person.

萧乾老人 is the object of 看望, means the aged named 萧乾.