The other thing is i have zero interest in holding any new btc from now on due to the price. So for example, if btc is price is 15000. Let say i withdraw 5000 usd so i get around 0.33 btc from the betting site to my bitcoin wallet. You say you could then wait a bit and if btc goes up, you can then sell your btc to usdt to get a higher usdt balance. But of course if it goes down and then you sell it for usdt, you get less. The thing is i don't want to have any bitcoin at these prices as its already way too high. Does that make sense? I basically only want bitcoin from now on only to buy altcoins... nothing else. So if thats the case, and since right now im waiting to buy certain altcoins but waiting for prices to drop, best to just withdraw whatever usd amount of worth of bitcoin i want now... so when the time comes when altcoins hit the low price, i could then buy btc immediately with my usdt and then immediately buy the altcoin right? Because i dont want to have to wait many hours or a day or even longer to buy an altcoin because at the moment, i need to withdraw btc from a betting site... then wait for btc to hit my wallet, before i could buy the altcoin via shapeshift. And since i want to use bittrex to buy altcoins, then best to just keep usdt balance there right? Of course i would like it if i request btc and then i get it sent to me immediately. That way i would send it to bittrex and then i wont even need to have itc converted to usdt since i would be buying it immediately right assuming prices is around the same?
Is not always necessary to convert USDT to BTC first then altcoins, some of the larger altcoins can be traded directly from USDT.
Yes , in your case, since you want a stable market value it would be best to keep USDT before trading, because Bittrex don't support fiat.
Depends on which exchange you like best, and if the exchange support the altcoins you want.
If you are just trading BTC, ETH,LTC and fiat, GDAX would be the appropriate exchange.
Well, as you said, sometimes it is because of the altcoins factor that keep people on certain exchanges. The prices can fluctuate a lot on different exchanges. GDAX may have higher BTC price right here and now, but the situation can drastically change in a few seconds/minutes, BTC is extremely volatile. As seen here https://coinmarketcap.com/currencies/bitcoin/#markets , the price gap on BTC right now is $5274 between cheapest and most expensive exchanges.
Sometimes you can get lucky and stumble upon sellers that dump huge amounts for under/over market price, and therefore drive the price up/down a bit.
Good luck with your trades!