Whenever you suspect a quotative 「と」, it would often help understand the sentence better if you actually put the supposedly quoted phrase in real or imaginary parentheses AND insert a verb after the と that you feel might have been implied by the author or speaker.
[早]{はや}く[花]{はな}がさくようにと、[毎日水]{まいにちみず}をやっている。
= 『早く花がさくように』と、毎日水をやっている。
= 『早く花がさくように』と([思]{おも}って、[願]{ねが}って, etc)、毎日水をやっている。
Despite your statement, 「思う = to think」 does fit there and so does 「願う = to hope」. 「[祈]{いの}る = to pray」 would probably be too much. 「思う」 in Japanese can contain the nuance of "to hope" depending on the context and this sentence belongs to such context.
「[感]{かん}じる」 does not fit.
「[言]{い}う」 would fit if the speaker actually uttered「早く花がさくように!」 when s/he watered the plant everyday.
= "I water the plants everyday hoping they bloom soon."
If you meant to ask us to do the exercize at the bottom, here are a few examples.
[少]{すこ}しでもやせられるようにと、____________。 Again, the verb implied after the 「と」would be 思い、思って、願って, etc. 「~~ように」 means "so that ~~". = "so that I could get as slim as possible."
Suggestions for the last half:
毎日2[時間歩]{じかんある}いています / デザートを[食]{た}べないようにしています / ビールをやめました, etc.
Finally,
いつ[帰]{かえ}ってくるかと、______。 The verb implied here would be 思い or 思って. 願う is not possible because it is about "when someone would return", not "someone returns soon". 「か」 must be used when a question word is used. In this case, the question word is 「いつ」.
Possible phrases for the last half:
ワクワクしています / [心配]{しんぱい}しています / [楽]{たの}しみにしています, etc.