Once granted a waiver, you can obtain a visa (usually one year at first). As a holder of a waiver you can expect long delays in secondary processing at the US border, even with a visa in your passport. Strangely, an exception to this is purely political offences..
Most simply explained, a constructive trust is an equitable remedy imposed to prevent unjust enrichment (see Simonds v Simonds, 45 NY2d 233, 242 [1978]; Sharp v Kosmalski, 40 NY2d 119 [1976]).
A revocable trust is a legal entity. It refers to a type of trust in which can be amended or revoked. The alternative to a revocable trust is an irrevocable trust. As the name suggests, an irrevocable trust is a trust that can't be revoked. If you have a trust agreement, it is one or the other. On the other hand a simple trust refers to a federal tax designation. The alternative to a simple trust is a complex trust. The tax designation of a trust can be a bit confusing but it is generally determined by how income generated by the trust is distributed.