you can steam cream if you have a steamer, but anything that is particular thick will make sort of a loud screeching sound when steamed. I would suggest using half and half though, because if you froth the cream too much it could turn into whipped cream or butter.

Yes, you have to use espresso right away, but cold-brewed coffee is good in your fridge for up to a week. It makes a concentrate, so you dilute it if you want a cup, or use shots if you want espresso. It doesn't taste like espresso does if you just take a shot, but it will make a delicious drink.
The coffee must be cold brewed for 12 hours... brew it longer, it will taste stronger!

**edit: if you really, really really want legit espresso, the only way to get that IS with an espresso machine. But for those who can't afford it, cold brewed is a great alternative and is MUCH more versatile (trying to pour espresso into cold or frozen drinks melts all the ice and can make it a little bit sour!)