What do you mean by maintain order? Same order name and price?
1) if my order is buy "STRATEGY 1 BUY" next bar at 1.0001 limit,
in the next tick, I MAINTAIN it at buy "STRATEGY 1 BUY" next bar at 1.0001 limit,
is it maintaining the same order?
Yes.
2) if my order is buy "STRATEGY 1 BUY" next bar at 1.0001 limit,
in the next tick, I change the name and have a buy "STRATEGY 2 BUY" next bar at 1.0001 limit,
is it considered a separate order? or is it still considered as the same order?
Separate order. The previous one will be cancelled, the new one will be placed.
3) if my order is buy "STRATEGY 1 BUY" next bar at 1.0001 limit,
in the next tick, I change the price and have a buy "STRATEGY 1 BUY" next bar at 1.0002 limit,
is it maintaining the same order? or is this a separate order?
If your broker supports order modification, the order is modified. If not, the order is cancelled and replaced.
For MBT, i read that limit orders are posted to the broker and not held in MC program, how is it possible if there is a cancel and resend on every tick? Or is this internally handled by MC program and transparent to us?
Orders can be either sent to broker directly or emulated within MC (depends on the type of order and whether it is supported by the broker). If your broker supports limit order (as far as i know limits are supported by most of them), the limit order is sent to broker. If on the next calculation the order is not generated anymore (condition is not met anymore), the cancellation of the order is sent. If an order type, let's say a stop order, is not supported by your broker, then it is emulated within MC: MC waits for certain level and then places a market order or a guaranteed to be executed limit order.