1. swap memory is created at the time of installing linux....you it may skip ...as it is not important (PC having 4gb or more ram) but it is important if you have 2gb 3gb or less than that
2.
i. search startup application in ubuntu (More info)
ii. untick or remove any useless startup apps
3. install this and clean junk file: BleachBit
4. don't know about any defrag app
5. yes you can run chromium on lubuntu
just a suggestion ....why don't you try linux mint ....It has both 32 bit and 64 bit ......if your computer is old or you have less ram you can install linux mint 32 bit (you can install chromium) and if your computer have 4gb or more ram then you can install 64 bit (both chromium and chrome is available for 64 bit) ... Choose cinnamon edition of linux mint
Thanks for you help.
Bleachbit is quite different from other cleaners but I have installed it.
Just FYI I am using Dell XPS M1530 laptop with 2.20 GHz Intel Core 2 Duo processor with 4 GB RAM.
Dell XPS M1530 Specs
When I bought it was one of the best laptops available at that time.It may be considered old now so I have to consider this while installing software.
Is there any software in linux which can password protect /encrypt pdf douments ?