You can ride year round in any of the States the border Mexico or sit along the Gulf Coast although for the best time this are is best from November to April. The rest of the country has good riding weather from April through to October with the exception of the Rockies and some of the other mountain ranges which can be ridden June through September.
Quite simply, unless you are just riding around town for a day or two we would highly recommend taking your own lid. The ones provided are very basic and not always the most comfortable for a longer tour. Some people get on with them fine but for others they just don't fit right.
Insurance is a very personal thing but in our experience nearly everyone takes out the full damage waiver insurance. This means ANY and ALL damage to the bike is covered so it's a big weight off. About 50% feel they also need to increase the standard 3rd part cover (included in the rental) with SLI (Supplementary Liability Insurance) This combined with the damage waiver cover will give the equivalent of Fully Comprehensive Insurance.
Within the bikes section on this site we review each model in more detail but simply the following is a good overall view:
Electra Glide: Two up, Maximum Luggage. A very big bike.
Road Glide: As per the Electra glide but with no top box so less luggage and a fixed fairing so a little lighter on the steering. Good two up or solo.
Street Glide: As per the Road Glide but with the Bat Wing fairing mounted on the bars. Some prefer the fairing sitting closer to them.
Road King: Still good two up but with the same luggage as the Road and street Glide. No fairing (music or sat nav) just a clear Screen.
Heritage Softail: As per the Road King, still good two up but lower in the saddle. A popular bike for smaller riders.
Low Rider: As per the Heritage but less suitable for a passenger.
Sportster: Unless you are really small these bikes are best on short rides around town. Can you ride one Coast to Coast? Yes, just don't expect to walk quite the same way at the end!
15. If the number goes over 15 a second sweep guide is added. Many more and a second guide and van will be added. The two groups will share hotels but will be 30 mins apart on the road.
Simply, Yes. Having ridden all over the US we have never felt unsafe. There are of course areas of big cities to avoid but if you are riding in any of the great riding destinations across the country you will not come close to any of them. Day to day you are far more likely to be held up by someone wanting to chat than someone trying to rob you. A bike is a great ice breaker and you should expect help and hospitality where ever you go. One word of caution. American police do not, as a rule, take well to chat back. If you are stopped, stay on the bike unless told otherwise and be respectful and business like in answering their questions. Only once they lead think about trying to be funny!