Yes, it possible, but not recommended for the reason already mentioned above.
Maybe it is better if you deposit your USD on an exchange and then start trading on altcoins. When you will earn more that 10$ worth of Bitcoin you will withdraw into your wallet.
Can you deposit $5 on an exchange? Is that enough to start trading with? And don't you need a separate wallet for each altcoin you trade or are those transactions stored on the exchange?
Like I mentioned above...I'm a complete newbie running on information overload. So many questions.
Don't worry, I know the feeling. It'll clear up after a month or two and everything will make sense, as long as you're patient.
You could deposit $5 on an exchange, yeah. If you wanted to do it on Coinbase for example, you could do it with a debit/credit card and accept high fees and ID verification.
On Coinbase you can buy Litecoin and ETH as well.
As for having separate wallets, yes and no. If you wanted to have full control over those coins and their private keys, you would be best off having separate wallets or using a multi-coin wallet like
Jaxx. However, for $5 I would personally just keep it in Coinbase's "wallet" and spend from there.
If I were you in this situation I would probably go for Litecoin due to its legitimacy and, dare I say it, stability. Good luck.