Does ambient temperature (i.e. winter vs summer) or food/drink temperature (i.e. cold vs hot) have an effect on voice:
I haven't found any trustworthy resources about the effect of hot and cold weather on the voice, so I can't comment on that. Humidity of the environment CAN affect the voice, for example the air conditioning in hotels or on airplanes can dry you out significantly, making singing uncomfortable and especially affecting tone (which may be what you mean by 'texture'?) of the voice. Various resources therefore recommend taking a humidifier to environments which would otherwise be uncomfortably dry.
The only problem I've noticed with hot/cold environments is that
(a) cold - shivering gets in the way of performance!
(b) hot - sweating can make you dehydrated, so you need to drink more water to compensate.
On temperature of food/drink:
Ice-cold drinks and food (like ice-cream) are considered not helpful for singing, as they make the throat tighten, making it harder to sing. I've personally found this to affect tone and my higher range.
Hot drinks (that don't contain caffeine) may be helpful. Although vocal cords are kept hydrated mostly through drinking plenty of water in order that your whole body is hydrated, organisations such as the British Voice Association also recommend inhaling steam, which can reach the vocal cords. So drinking hot water may provide the dual benefits of hydration and relaxing the vocal cords. I don't know whether this has a directly beneficial effect on tone or range, but I have certainly found it to help stamina when I've had a lot of singing to do over a short amount of time.
I can't find any information about the effect of hot food or very hot drink, so I hope someone else can comment further.
It's worth mentioning that caffeine and alcohol have a diuretic effect. That not only makes you go to the bathroom, it dehydrates you, and can reduce the amount of saliva and mucous available to your mouth and throat and larynx. When you sing and your mouth, throat and larynx feel dry and don't have lubrication, you fatigue your voice, your tone suffers, you may have trouble singing high notes or long sustained phrases, and you may cough while trying to sing. In the long run, you can damage your voice if you continue to sing while drinking or eating caffeine regularly. It's a common cause of frequent laryngitis.
Some people are much more sensitive to this than others. I recommend that you don't drink or eat (as in chocolate) any caffeine during the time that you'll be practicing singing or performing, and see if your voice feels better and your tone seems stronger and more free, with less fatigue.