For the handheld, you are pretty limited unless a) you have repeater coverage where you are at or b) you can get to high ground to get line of sight. A better option is to get a mobile radio that can cross band repeat and a GOOD antenna for your vehicle. Then you can program in a random, little used frequency between your handheld and the truck--then the truck can rebroadcast your transmission at full power on your chosen frequency with the better antenna. There are also modes where you can link two radios together to make them alert you when you are no longer in range of the other radio. Depending on what/where you are going/doing, a mobile HF rig with a lithium battery and a precut wire to string up in a tree can allow you to talk around the world--too heavy for a long backpacking trip but doable for a shorter trip. HF will always get you somebody to talk to--not necessarily in the same geographical area, but it WILL be somebody with access to a telephone and a willingness to help. A popular rig is the 817d because it can do HF, VHF, and UHF. The rub is that it will only put out 5 watts--low power operation is great but I'd recommend getting something that you can put out more power if you need it. I'd rather be able to transmit at 100w for 10 minutes and get my message out successfully than transmit for 4 days and not reach anybody.
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To your other question, 146.520 is on my scan list so anytime I am mobile I am scanning it--it is a solid bet that you can reach somebody, even if many won't respond to a CQ, they will respond to an emergency call. The other very useful feature of HAM radio is access to communication during extreme weather events--the skywarn and ARES organizations are very useful. We had a rare tornado in Virginia Beach about a year ago--I was able to track the exact location of the tornado via the spotter reports on the skywarn net when weather radio simply said "get inside, there is a tornado." It ended up passing about a mile from the house, but still closer than I would have preferred.
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Beyond the scope of your question, but may be useful info--look into APRS, either HF or VHF/UHF--if you have coverage and the right radio you can connect a cell phone to your radio and send short emails or text messages. These data packets can be transmitted and received even when voice transmissions are unreliable. This can be extremely useful depending on location. Where there is no UHF/VHF coverage, HF will get the job done, but still needs the radio, antenna, etc--bulk and weight.
