Ditching the dish; seeking OTA acvice

I ordered my directtv disconnected today and I'm going OTA. I tested the 30-odd year old pre-digital TV antenna and got even more channels, in HD no less, that I had hoped for. Enough, in fact, to make Mama happy (on balance, in light of the $100 a month savings). But I need some advice from folks with antenna TV experience. #1, Am I saving myself long-term heartache if I replace the twin lead cable (which runs from the wingnut terminals on the antenna and terminates in the living room) with coax. IOW, coax all the way from the antenna into the house? On the one hand, back in the stone ages, the twin lead cable was always the weak link in the system. OTOH, it's survived as is at least 20 years, and if I disconnect it, I'll never get all the corrosion on the connectors lined up as perfectly as it is now, so why mess widdit? Yes? No? Maybe? #2, Is there a rule of thumb regarding how far OTA signal can travel by cable before an amplifier is necessary? From the top of the antenna to the furthest TVs, I'm looking at a cable run of about 100 feet. I intend buying the digital-audio converters online, and if an amplifier is likely to be necessary, I'll just throw one in to save on the shipping. Tips and advice also are welcome.