New Mac Mini user

New Mac Mini user here, decided to switch from windows. I have a mid 2010 mini equipped with an intel core 2 duo 2.4ghz, 8gig ram, 1TB hard drive and is currently using OSX version 10.6.3.
Having an iPhone4s and iPad 2 I like the convenience and functionality of working with Pages and Numbers and having the documents shared between those devices via iCloud.
From my current readings I understand that I must upgrade to OSX Mountain Lion to enable iCloud sharing. My questions are:
Is 8 gigs of ram sufficient for Mountain Lion ?
I have read the upgrade to Mountain Lion slows some machines down is this true ?
Any advice will be appreciated. Thanks.

Except for the resource hogs of Safari and Firefox - am running ML with 4GB just fine.
If I didn't use both of them simultaneously, I'd probably ok here.

8 GB should be plenty.
It's going to slow down machines that are only using 2 GB RAM.
Could slow down some that have older software not upgraded for ML.
You shouldn''t have an issue - especially if doing a clean install.

Will "assume" you've bought this mini used... in which case, would recommend you repartition/format the drive and do a clean install of ML rather than doing an upgrade install. This will, of course, delete everything on the drive. Regardless of whether you do a clean install or an upgrade install, you should have a backup of any data you may not want to lose prior to beginning.

Also, recommend creating a ML boot disc after you've downloaded it and prior to installing it onto a flash drive - the easy way.

Yes, I did purchase it used. A clean install of the original OS was performed. Do I have to go the upgrade route or is there an install disk for Mountain Lion? Is there a difference and how do I repartition the drive. Please forgive my ignorance as this is new to me.

Before you can get Mountain Lion - you will need to upgrade to 10.6.8 - use the combo update here - after updating open the App Store icon you'll find in the dock, download ML - it is only available as a download.

After downloading it, create the boot disc per the link above.
Then reboot the system while holding the option key and select the flash drive to boot from.
Once booted up, select Disk Utility from the menu
Highlight your internal drive on the left - very top item
Click on the Partition tab - select 1 partition from the drop down - name the partition and click Create
When that is done you'll be back at the dialogue and this time select Reinstall OS X.
Next thing you know, you'll be booting up into ML.

One more tidbit - since you have a clean install already and I'm guessing none of your own data on the drive as of yet - you can forgo the backup "if" the original owner gave you the Snow Leopard discs that came with the machine. If he did not give them to you, I would still highly recommend you create a bootable backup (that you verify works) prior to installing ML (can use SuperDuper! or CarbonCopyCLoner) - just in the unlikely case you desire to return to 10.6 at some point in the future.