FLV joiner and splitter and FLV converter

I am looking for some of the FLV softwares which can split FLV videos, join FLV videos. It’s not necessary that i need all in one

Also if any one know some kind of software which can convert wmv or avi files to flv i mean to say reduce the file size from 700MB to less as normally done by converting it to flv ( a little low quality but good viewable)

Please assist me

Thank you