Since your usage for 10 sites is just 2GB you can go for any shared hosting packages. Even the basic one's offer like 20GB bandwidth plan a month. That is quite enough for you.
How long is a piece of string? Seriously, its almost impossible to tell. If you have needs that are large and growing, you might perhaps consider getting your own dedicated server. This would offer you great flexibility, better power, and nearly unlimited space which you seem to require.
You can search digitalpoint or webhostingtalk and I'm sure you'll find a host that will suit your needs best
Hi, We had straight 100% uptime for months on our shared hosting, but what happened on that day brought it down. Our DC was experiencing issues from their upstream provider so thats why the downtime was so long. We kept everyone updated on what happened. If you contact us we can provide credit for the downtime. - Prilep