Here are some tips:
I am on a 6 year's old laptop with quite fast internet connection though.
don't use a laptop, you probably need your own server. Some people are running VPSes, but eventually dedicated machines under your own control would be preferred.
I have 2 standby delegates and If this helps the network and you vote for me, I don't mind keep the GUI run for a couple of days.
if you're a delegate, you need bitsharex and your computer to run uninterrupted for years, not days. Also, don't use the GUI you really should be running a dedicated and stable server with the CLI.
I don't know how to submit price feeds or anything like that...
There is a manual CLI command that is easy, and there is also an automated script here:https://github.com/Bitsuperlab/operation_tools/tree/master/btsxfeed
Once hopefully I make some money from BTSX appreciation, the plan is to buy a proper PC and keep it open running all day but until then does it make sense anyone to vote for me or it is better not since I may risk to destroy my reputation?
It's probably best to not be a delegate until you're a little more comfortable with technical side. This will take some effort. Read about linux server administration, how to compile binaries, and how to use the bitsharesx CLI.
Should I post on 04.10 thread that I am a standby delegate up and running?
you can, but there are over 1000 other standby delegates - it's probably better for you to get more comfortable with the technical side before really pushing to become an active delegate
What kind of PC specs would you advise me to go buy in order to become a useful delegate who really wants to support the network?
don't buy a PC, instead look at getting a VPS (linode, rackspace, amazon, google, digital ocean) and eventually plan on getting space at a local data center.