These questions always bothered me...
Some of them are stupid but... cardassian curiosity is killing me

!
You stirke me as new to this forum, as these are all farily beginner questions. But that's fine, we all start somewhere and I'm happy to help.
1st. Have u ever wandered where all the garbage and biological waste from toilets and other stuff is dumped in starship? Simply in space or there is other solution?
It's reprocessed. The stuff that is not usable at all is crushed using a high gravity press into inert cubes and stored til a starbase visit. The rest is cleaned and reprocessed into the basic material the replicator uses to generate new food.
2nd If the replicators can replicate very complicated spare parts of all kind of technology is that mean that gigantic replicators (with powerful energy source) could replicate a entire ship??
No. The replicators are pretty much energy hogs. Using them to make small items is not so much, but the bigger and more complex the item the greater the power requirements. So it just makes economical sense to manufacture things using more conventional methods. Also, there are numerous materials which simply cannot be replicated (such as latinum) and we must assume that such materials are required to build starships. There are, however, large scale industrial replicators, we hear of them in DS9. But they are rare birds indeed, there being something like one or two on all of Bajor and not many more in the Cardassian Union. So, I guess you could say there is a point of diminishing returns for replicator use and replicating whole starships isn't practical.
3nd How Quark manages to make a profits from drinks he sales ???I mean there are replicators all over the station ,why pay when u don't have to??
Most Federation replicators produce synthihol instead of the real deal, and we might assume that the Cardassian replicators on the station have the same restriction. For all we know, it may be that the alcohol molecule is one of those things that don't ever replicate properly. Quark has the good stuff on hand. Even if we don't assume the replicator
can't make alcohol, we can assume that it's programs are limited and Quark has a wider selection. At any rate, I think most of his profits come from holo-suite rentals and gambling. After all, his place is half casino and casinos aren't successful because they also have bars...
4th If holograms can be set to kill mode, why everybody just don't built holographic war ships?
The "kill mode" is just that the holodeck won't take precautions like automatically disappearing a prop bullet or bit of shrapnel and that might cut into and damage an unarmored person. After all, the props in a holodeck are physically replicated items controlled by force fields like super-tech puppetry. Normally such a prop would be removed by the safety programs if they threatened a person, but this feature can be shut off for some reason. Warships are well protected from that sort of thing and I doubt a holodeck can create a working phaser. Note that when Picard went to the holodeck and turned the safeties off, he blew away the borgified Ensign Lynch with a tommy-gun, not an energy weapon. I'm sure he chose this program partly because he knew a fake holographic phaser wouldn't do the trick.
5th If time travel is discovered by so many races ,hows that no one of them tried to change past in global sizes?
Sometimes they do. See "Year of Hell" on
Voyager.
6th How different races produce offspring when there is big anatomy or DNA difference?
Shouldn't that end in some kind of mutation?
All humanoid life was seeded in the galaxy billions of years ago by some ancient race of proto-humanoid aliens. It was explained on "The Chase" on
Star Trek: the Next Generation.
7th Space is full of resources, there are many planets that are entirely formed of metal or other valuable ores ,hows that galaxy is not swarming with huge numbers of ships?
This actually is not true at all. All worlds are formed of a unique collection of ores and minerals (and gases...). What's more, starships are made of complex alloys and manufactured goods, not raw mineral. Such resources need to be found, gathered, processed, and used to make a ship. Not to mention the fact that you need ship yards and a whole infrastructure to support them. Also, there is the bureaucracy needed to organize such large scale projects.
Star Trek has always shown us that the future is in many ways, not so different from how things are today, at least where this sort of thing is concerned. Remember one of McCoy's closing lines in ST4, "The bureaucratic mentality is the one constant in the universe."
8th All crews we saw in star trek series are most of their time in ships or stations ,how they don't get sick because they eat replicated food,air is always the same,no sun,and they rarely exercise?
They have holodecks for "getting out." Besides that, most of the crews we've seen have periodic away teams to explore places, so they get some sun. There are the more remote locations, like sub-space relay stations and that sort of thing, but I assume those are fairly short postings, like astronauts and cosmonauts serve on the I.S.S. Plus, the medical technology of the future probably helps compensate in some valuable way. but I assume it can be a problem, especially during TOS, where in more than one episode, McCoy was griping about the crew needing some much deserved R&R.
Hope that helps!
--Alex