I want to be sure in what order services are started during boot process in Debian based systems (Debian Squeeze in particular).
Thanks in advance.
This shows you what starts at which runlevel, and within each level the order is determined by the number after the letter (K is Kill, S is start).
You can configure what starts at each runlevel with sysv-rc-conf, which is installable with apt.
e.g. on my system apache2 is symlinked in rc5.d as "S20apache2". A link in the same directory with S19 would start before it, something with S21 would start after it.
Would rcconf and sysv-rc-conf utilities help?
Afterwards you can run them by typing
On Debian rcconf should do the trick, just to configure stop/start of already present services.
I use it all the time on Debian Jessie and Wheezy.