Martingle Confusion

I've blown 10% of my equity on my first day of real account trading when I tried this approach for the first time two months ago. But I've grown up since, and I now know the risks involved with this strategy. However, I'm trying different ways on demo to come up with a better something. But I'm confused with bid/ask, so I hope you can help me out a little.

Question 1: SL and TP

Which is a better idea?
(a) 10 pips SL and 20 pips TP
(b) 20 pips SL and 40 pips TP
(c) 20 pips SL and 20 pips TP

Question 2: Pending Order

Let's say I wanna trade EURUSD at 1.2450 considering 1(a) and 2 pips spread.

Sell Limit: 1.2450, SL: 1.2460, TP: 1.2430

What should be my second pending order so when one closes, the other opens at the same time.

e.g. Sell Limit: 1.2460, SL: 1.2470, TP: 1.2440

How do I insert spread into this? Should I sell at 1.2458? What about SL and TP? I mean I'm confused about when to go with ask price and when with bid price.

If I could make you understand what I'm confused about... could you please explain?

Question 3: Cancellation

If I trade on MT4, is it possible that when one TP is reached, the remaining pending orders are canceled?

Thank you

Q1.
that depends on your strategy.

Q2.
i don't know how you put your entry position, so i'm not commenting not that.
but i can tell you about bid and ask
Ask is for opening a buy order and closing a sell order
Bid is for opening a sell order and closing a buy order

Q3.
there's no setting for this, you have to either do it manually or have an EA to do this

1)None of them is a good idea for someone of your trading skills for now. Those are very very small stops and TP which suggests that you are intratrading on 1hour charts or less. Judging from the way you ask your questions, you have not grasped the true concept of money management. I suggest trading on a higher time frame to allow more room for error and so that you have more time to learn about money management.

2)Unfortunately this really depends on your broker. Each broker has different settings especially with regards to MT4. You will have to experiment. Just place a very small trade size and figure it out. Word of caution: You shouldn't be this worried about spread at this point of time because you should'nt be trading intraday. Only the big boys or the more experienced are privileged to worry about spreads.

3)Not possible on MT4. You need to manually do it or write an EA to do it for you.