You can edit new pictures or additional info into posts of your own which already exist, and one way (which is a bit more work) is to click reply to one post, copy the contents and click cancel, then reply to another post and paste the contents of the first - this way you can still reply to multiple people in only one post. The reasoning for multiple back-to-back posts being merged together is that if you have one person posting multiple things back to back, it stretches the page more than having all of the same info in one post (due to signatures and names, etc. taking up space). Merging the posts together keeps it more organized and stretches the page a bit less. Also, as Jeremy pointed out, you could switch browsers as a temporary fix to the bugs you mentioned.