My ecommerce site has good page 1 rankings on Google but the host it is with is dead slow, I need to move to a new host company but will it affect my search engine rankings in the short term?
No, IP address and DNS changes really don't affect ranking at all. I only find that email reputations are affected. If you have a big email list on that server, it might be some work for you. Your SERP shouldn't be affected at all.
configue a 503 or 501 - one of them - this tells the se that site is currently unavail and come back later... sometimes you get cached in the move... and so this will pull a new snippet n such - which can eefect you conversion rate... but config the 501 and you should be ok....
yes sometimes it may affect to your site as "G" eye may not consider a sudden change an pull its position to downstage.Therefore you must definitely configure 501 to stick back to the same!!!
No it won't ... just make sure that your new site layout is identical to the old one or that you have the relevant 301 redirects in place.