Thanks for writing your suggestions.
For the first suggestion dealing with the Recent Posts page, that page is just for recent posts, and expanding the page size would only have the effect of slowing down the site. (That's why the page sizes are kept to a "reasonable" size.) Instead, I would suggest you use the Search page if you need to find very old posts by a person. You can click "Username", type their Username, and go directly to any page of results for the person. You can also filter by depth of history (time) to search, as well as the specific forum they posted in. The page defaults to searching the past year of posts, but with a click you can set it to all history if you like.
In addition, the other categories of searching on the Search page — All, Forums, News, Tag, Blogs, and Private Messages — provide many other ways of finding information about a member or subject.
For the second suggestion, I would recommend that you use the excellent AutoSave feature built into the text editor to send the same post to different people. You simply click the "life ring" (AutoSave) icon on the toolbar, and your previous message text is instantly recalled.
I would warn, however, that bulk mailings to many people will be interpreted as spam by the system, and will shut down your account. If you're sending something to a few people that will be fine, but don't try to mail everyone you know with the same text.