First of all, voting laws vary by state. So if you want advice for yourself, you should really be asking other residents of Texas. Ideally, the
Texas Secretary of State would have a
web page with all this information on it. I clicked through it briefly but I don't know how helpful it is. If not, try one of the two political parties' websites. It's in their interest to get their own supporters to get out and vote so they usually have pretty detailed instructions on there.
They will also tell you which candidates they are endorsing, in case party affilitaion is not listed on the ballot. This is also the place to find out what seats are being contested. The more local the position, the fewer people eligible to vote for it and the more your vote counts. Personally I pay the most attention to school board candidates in case any creationists, ultranationalists, or other wingnuts try to slip in.
I can't imagine you would have to vote for everything on the ballot. In
Minnesota, you have to mark at least one vote for the machine to accept it.
In Minnesota, you need your ID to register but not to vote. I always bring mine anyway because no one can spell my name. You can register on election day (with ID) and you never have to declare a party affilition, even to vote in primaries (but you can still only vote in one party's primary). Most states require you to register in advance.
You have a constitutional right to make a write-in vote (a vote for someone not one the ballot), but the state doesn't have much responsibility to make it easy for you, and they no longer have to count them. I like to write in joke names for races I don't know anything about or when there is only one candidate running.
In my state incumbent candidates (people already in office running for re-election) have "incumbent" typed next to them on the ballot, so if you want to throw all the bums out it's easy to vote against them all.
Our Secretary of State wants to require us to show ID when voting but so far the state Senate is blocking it. I agree with her; I think the current system is vulnerable to fraud. You can already register to vote automatically when you get a state ID card. On the other hand a state ID or driver's license costs money, amounting to a poll tax if your require ID.
In short, it is super easy to vote in Minnesota but most of you pussies (excluding some Canadians) won't move here because it gets a little chilly for 8 to 10 weeks a year.