Yes indeed, within 1 hour cruise speed in still air with 1 engine inoperative. Dont quote me because it varies with airplane, but does 270nm also sound correct for mileage that TO alternate should be within?
And for ALL alternate weather minimums, Part 121 carriers often use derived minimums using an opspec C055. Basically if your alternate airport has only one appropriate navaid and approach, you have to add 400ft and 1sm to the highest ceiling and vis but if there are two separate navaids and approaches that could be used, you only have to add 200ft and 1/2sm to highest ceiling and visibility.
Using this method makes the possiblilty of using an airport as an alternate feasible with crappier weather than the standard 800/2 600/2 mins. Remember this method is used to calculate minimum legal weather to file as alternate, destination or takeoff. Hope this helps for any CFIs out there!