Would that be even possible ?
Yes, obviously. While the Ausgleich wasn't a spur of the moment idea, there were alternatives, but you'd need to go further back to get them to replace it.
Prior to 1848 the concept of a sort of federation based on the crown-lands was popular among the conservatives, but due to the issues of, well, the rule of Franz I. (who was utterly opposed to any reform) and the fact that the regency council couldn't operate openly during Ferdinand's rule pretty much meant that there was no opportunity for such a reform to be pushed through, even if there was the desire to do so (and there was, Metternich was, for one, a supporter of the idea).
How would this affect the Monarchy ?
If we go with the conservative plan? It would provide a base for later reform. They were conservatives, so the parliament was, at best, an advisory body (Metternich had
weird ideas),the voting franchise would be very limited and so on. There were some provisions for autonomy in language and culture, as well, pretty limited, but more than anyone would get for quite a while (inside the Monarchy, of course).
Basically, you could have a federation emerge from it. Expand the franchise, expand the parliament's powers and you'll get a centralized federation with some autonomy on the local level (provided that doesn't get expanded as well).
would Hungary seperate from the Austrian Empire ?? Would there be a Civil War which breaks the whole empire apart ?
It depends on the way things develop. The Hungarian attempt to separate was based on the notion of an independent Hungary. That idea would likely still pop up, perhaps in a more limited manner, but nevertheless. So, yes, there's likely to be a Hungarian uprising, though possibly with less popular support. Of course, like OTL, such an uprising is likely to be crushed.
A civil war? It didn't happen OTL with the Ausgleich, so I'd take a gander and say no. The Poles had a good thing going and never caused problems and the Czechs kind of didn't have anywhere to go and they knew it, so they limited it to being obstructive over and complaining over which part of Czechia goes where (in the above scenario this would be solved, since the crownlands were intended as the basis of the division, which pretty much means all of Bohemia is a single unit). I seem to remember a botched attempt at a Croat uprising that only really affected a couple of villages before being promptly put down, so there wasn't much support there either. The Italians did, but they did it in conjunction with the larger moves towards a unified Italy and during a war with Sardinia-Piedmont over Lombardy and Venetia, so ... there's them, I suppose.
I think a stronger army and perhaps a reformation to a federalized Empire would be more likley without the Ausgleich.
Not quite, some form of change is necessary
before the Ausgleich. Simply put, Vienna needs to set up a power-sharing agreement with someone. Basically, it's Ausgleich or taking the federation route. Austria's issues need to be addressed pretty early.
The army would be stronger, certainly. No divided budgets or wrangling over who gets what and such would help. You're also more likely to see a better economy and, as a result, knock-on effects on the army proper.