A. Yes, the shortcut executes the opening of the LimeWire program.

B. Oracle Java 7 (build 1.7.0b147) which is the newest version. I am not sure it should matter if you are using the FX version. But I do not know the answer to this. I suspect it will work fine for you.

(1) LW 4 search filter: It is highly recommended you do have those options checked. Yes it will filter those items out. Adult content filter would be aimed at reducing porn in search results. html files are useless and possibly dangerous. vbs files are rather useless also unless you had the info files that came with them. wmv and asf files are commonly spammed and frequently infested with virus. It's best not to trust them, thus filter out. For improved filtering, I would recommend seeing filter words and in general, see How to find Music and Videos though you probably already know much of that.

(2) OOB is best left enabled if possible. What it means is, searches will go a little further, I suspect bouncing over some peers to reach peers further on in the chain of peers. If you suffer any kind of performance issues though, disable this option. Sometimes OOB can affect LW's connection.

(3) Search results are usually a result of the ultrapeers you are connected to. I just opened 4.18 on Win XP and received good search results. It can sometimes be worth changing your hosts. ie: go to menu bar, View > enable Connections window. Remove the first on list. Wait several minutes and see if things improve. As a general rule, the longer you are connected, the better your search results should become. Remembering also that the network is rather dynamic, people frequently come and go and connections change.

Someone complained about connecting to mostly or only Japanese hosts whom use Cabos. I have noticed this issue for a reasonable period now. But at least on this occasion of connecting with 4.18, only one of the hosts were from Japan.
Remove any hosts you see using a version, LimeWire 4.21.1 (RC), these are spammers.

Personally I preferred LW 4.14 compared to 4.18, but it can depend on a person's system or personal experiences. I also liked 4.16 but 4.14 was far better IMHO.