Do you add frozen peas directly to flavor bases or you have to boil them

Unless you freeze them yourself and don't wash them first, no, you should not need to wash commercially processed frozen vegetables. Part of the process for freezing includes cleaning/trimming preparing the vegetables. Washing is unnecessary.

Info here:

The actual process of freezing a food item varies somewhat depending on what is to be frozen. Peas are the most common frozen vegetable, having virtually replaced fresh peas in the American supermarket. The pea process is typical for many vegetables. A typical process for a frozen entrée follows.

Picking and washing

• 2 The peas may be picked by hand or automatically. Then, a machine called a viner removes them from their shells. If the processing plant is adjacent to the fields, the peas are carted there. If truck transport is necessary, they are cooled with ice water and then packed in ice for transport. At the plant, the peas are dumped into beds and sprayed with water to remove dust and dirt.

Sorbet are typically acidic(from the fruit juices) and contain sugar. Both of these act as preservatives in addition to the extremely cold temperatures that sorbets are kept at. So it is perfectly okay to melt your sorbet ice block. However when you melt the sorbet block, you will want to do it slowly. Fruit/herb flavors are very volatile so if the mixture is over heated, the flavoring will break down and the taste will deteriorate.

When refreezing your mixture, you might want to consider adding a little more sugar into the mixture to prevent it from freezing so hard in the future. Sorbet sugar by concentration is usually around 20-30%. If your sorbet is sweet enough, then you may also add a little tasteless alcohol like vodka to prevent the sorbet from freezing too hard.