Leverage does not affect crypto pairs, that is the difference.
Example: 1 lot for crypto is 1 unit of cryptocurrency. If you want to calculate the USD margin for 1 lot of BTCUSD, take the current rate of 1 BTC (9000 USD)x0.2(margin rate) = 1800 USD margin.

Cryptocurrencies can be traded 24/7 any day, with minor exceptions mentioned in B2Prime specification (MT servers restarts).

No, there are no swap charged on PrimeXM and OneZero level on the weekend

There is no spot trading on marginal accounts, you get only the difference when position is closed, thus 
you are not able to do it unless your margin account currency is BTC.

Number of lots*point price*delta(points),
for example: you have an open position 10,000 XRPUSD. You opened a long position at price of 0.2, closed position at 0,21. 1 point at XRPUSD = (contract size*tick size) = 0,00001 usd. Delta is equal to 0,1 usd =10,000 points. Your profit is 10,000lots*0,00001usd*10,000 points =1,000 usd.

Charts in MetaTrader 4 and 5 are based on Bid price. If a buy limit order was placed, it must be executed with an ask price. There is always a spread between bid and ask, this is a usual reason why.

The PnL will settle on your account after the rollover. It takes place on Saturdays in PrimeXm
For OneZero the rollover rules are: for FX instruments [T+2 (in 2 days), or T+1 for USD/CCY2 and CCY1/USD pairs where CCYx is of [CAD, TRY, PHP, RUB, KZT, PKR]. T+0 for all other instruments.

You will get a notification via email from b2broker support team.

Your positions will be forced to close and you will get a notification from B2Prime team about the positions that were closed.

It is recommended to keep Used margin on the level of 65-75% to avoid Stop Out. Possible options:
1) Deposit additional funds to your margin account
2) Close part of your open positions

In case of Stop Out positions are automatically closed on PrimeXM/ OneZero level, but will remain opened on MT 4/5 level. Stop Out level is 120%.

But in case positions of your clients get closed by stop out in MT4/5, respective volume will be closed on PrimeXM / OneZero level.

PnL is credited to margin account balance only after rollover, which is on Saturdays in PrimeXm. For OneZero the rollover rules are: for FX instruments [T+2 (in 2 days), or T+1 for USD/CCY2 and CCY1/USD pairs where CCYx is of [CAD, TRY, PHP, RUB, KZT, PKR]. T+0 for all other instruments.

There are several definitions of rollover:
1)It is a process when positions are shifted to the next trading day. Rollover is proceed automatically every day at the fixed same moment of time. During the rollover spreads can be expanded, thus some positions can be closed by Stop Out in case of the too high level of the Used Margin. So it is recommended to keep the level of the Used Margin on the level of 65-75% This rollover is a global interbank event and we have to deal with it.
2)It is a moment of transferring Pnl to balance. It concerns only PrimeXM and OneZero.

Every working day and there is tripple swap on Friday.

Technical support will inform you about the upcoming changes of swaps by email before they will be applied on the trading platforms. All relevant information you can find in B2Prime specification.

You can calculate margin level(%) if you know how much margin it takes to open or maintain a position, and your current equity. Example with FX instrument:
1 lot EURUSD. 100,000 EUR (in USD)*Base currency rate to USD(1.13/1)(EURUSD rate)*margin rate in specification(1%) = 1130 USD. Formula for margin% = (used margin(usd))/equity(usd)*100%.
Example: you are going to open 1 lot EURUSD and your current equity is 100,000 usd. In this case opening 1 lot EURUSD will take 1130 USD(as per previous calculation) and final formula = margin/equity*100% = 1130/100000 * 100% = 1,13%

Formula for CFD: number of lots*point price*delta(points).
For example: you have an open position 1 Buy AMZN. 100 points on 1 lot AMZN = (lot*contract size*tick size) = 1 00 usd – this is your profit for 100 points price movement on AMZN

You can take swap data from B2Prime specification here.
How to calculate swaps according to your position:
2)Formula for swaps calculation: Let’s say swap long for USDCHF is (-5). Then swap charged for keeping 50,000 USDCHF open on USDCHF = 50,000(contracts)*0,00001(tick size)*(-5)(swap long)*convert rate (as an example let’s take usdchf=0,95000 so chfusd=1,05263) = -2,63 usd.

B2Prime Oil price – The price will trend towards the future gradually over the period of the next expiry, it is a SPOT product, not a CFD on the future.