If replacing the battery hasn't helped, something else is going on and you're probably going to need to replace the phone. MicroUSB and similar-looking ports can be fragile - or maybe there's a short somewhere - either way, unless you have an independent repair shop near you or you're comfortable trying it yourself (what do you have to lose, after all), you're looking at a new phone.

If the people you communicate with the most prefer texting, then I can't even begin to describe how much quicker it is NOT to have to hit a keypad button three or four times for every character to spell out a word.

It is an extra expense - but assuming you're going to have some phone, then look at the extra expense when you consider whether it's worth it, not the total. The difference between my current voice+data+text plan vs. the minimum number of minutes with a basic phone is $30 a month.

Battery life is definitely a consideration, but I don't necessarily trust manufacturers' claims on that. Talk to people who own phones that you're interested in, and/or visit online forums (there are lots).